A/N:YUP! Update already! Enjoy that last part, thank Ultharkitty and have fun.

Optimus seemed to relax completely at the endearment.

Ratchet pushed him with a finger, and the young mech collapsed on the berth giggling. "Your spike is unsealed, so if it pressurizes when I touch your valve, just do what you feel like doing."

Optimus looked fearful for a single moment, but then spread his legs and looked at Ratchet expectantly.

"Nnnngh." The sound slipped from Ratchet's vocalizer unbidden. "This... Optimus, do you have any idea..."

The young Prime started closing his legs, but Ratchet stopped him.

"Frag, please no!" He was loosing his head for this mech. "What happened? You seemed so reluctant at first and now you are tempting me, making me loose control... Please don't... I love every moment of this, every glance at you. Everything that you are doing..." He shouldn't be saying that.

"I don't know. "Optimus' field flared with embarrassment and rising heat. "I... Overloaded," he tasted the word, Ratchet realized. "When you put my... my spike in your mouth and it felt so good so... Finally... And I want you to make me feel this good again." He admitted. This innocence, sincerity of his shining through his optics and sounding in his words. "I'm doing what feels... Right. Wasn't it what you wanted me to do?" His voice was barely a fidgeting whisper.

"Yes, Optimus, yes. Primus knows I want you to do it." He was kissing the young Prime before he stopped talking, the mech kissing fervently back.

Optimus' hands caressed his armor, unsure, clumsy, but with underlying need and desire.

This time Ratchet took time to explore the chest and abdominal plating. He caressed slim collar reinforcements and slid his hands under bounding frontal armor. When he run his fingers over white frontal lights they flashed in excitement, and Optimus pressed into his touch, whimpering helplessly.

Then came the deliciously slim, gray waist, a work of art when it came to plates overlapping so perfectly the seams were barely visible on the sides, yet it was the central seam he paid most attention to. It was the new rage of the season, the deliciously round spheres that made the mechs so much more agile, that were so sensitive.

He slid his full palm over the center sphere. Optimus' field flared wildly as his optics snapped open, and a loud cry of pleasure ripped from his lips making Ratchet whimper needily.

"Too... much." He tried to calm his ventilation, and make his vocalizer work, but one more brush of the central sphere and he was crying out again in abandon.

"Shhhh" Ratchet managed before he caressed blue hip fairings, enjoying the slide of smooth metal under his palms. So perfect.

He skipped the interface array to kiss beautiful thighs. Strong and shaped by the hands of an artist. He kissed the edges of the armor plates, laden with sensors necessary for transformation. He slid his glossa along the seams eliciting moans and whimpers and uncontrolled lashes of Optimus' field.

His hands explored sensitive sides, delving under the armor and caressing inner wiring. He nibbled on the groin seams gently earning a long keen, Optimus' hands going to his head.

He took one hand and licked one gray finger.

"I'll switch on your lubrication systems. It might feel weird at first, like you were leaking."
Ratchet pressed a finger into his valve gently, just past the rim, and engaged the connection again.

He traced the edge making Optimus groan before encountering a firmer bundle of nerves and pressing. Optimus cried out in pleasure, his body arching off the bed as subroutines engaged.

He withdrew the finger and Optimus shifted uncomfortably.

"Ratchet it's... Weird..." He tried to close his legs, but Ratchet held them watching the opening, eating up the picture of the freshly lubricating valve.

"Mmm it's going to make you feel so good." He moaned optics glued to the moistening orifice. "...And taste good." He leaned forward and licked the lubricating opening, lapping at the fluid that started to leak out. Optimus yipped loudly before keening and thrusting his hips forward.

"This... Oh, Ratchet." He moaned when Ratchet pushed his glossa deeper, then slid a finger beside his glossa and thrust it deeper still.

Optimus arched at the additional, firmer intrusion.

Ratchet withdrew it and his glossa and thrust the finger back again, the exquisite tightness hugging his wet digit and pulsing, beckoning him. He withdrew it and lapped at the valve again, losing himself in the taste of the young mech. He loved this... Taste, smell, nothing tasted as good, as sweet.

He thrust two fingers back in. Optimus thrashed, his legs trembling as his vocalizer whined.

Ratchet moved his fingers in and out slowly, watching for any discomfort, checking over the connection for any pain, but there was none. Optimus felt the stretching, but his sensors read it as pleasure. Every slide of Ratchet's fingers made his valve relax, inner walls squeezing and releasing, Ratchet's fingers now soaked in lubricant.

"Please." Optimus whimpered.

"Do you want more?" Ratchet quivered, his spike slowly pressurizing again.

"I don't... ah!... know."

"Give me your hand." Ratchet urged Optimus, and the young Prime reached toward him. The medic guided the trembling hand to his interface equipment. "Can you feel it?" He touched black fingers to the rim of Optimus' own valve where his fingers worked it open slowly.

Optimus' field flared in sudden arousal, he put his own hand at Ratchet's and held his wrist and rocking his hips pushed medic's hand to the hilt.

"Oh Primus!" Ratchet watched as his fingers were swallowed. Optimus moaned and thrust his hips again

"Nnnngh... Deeper... RATCHET, PLEASE!"

Ratchet scissored his fingers, feeling around, setting off the sensors and the young Prime rode him, pulling Ratchet's fingers out just a fraction then pushing them back in.

Fragging himself with Ratchet's hand.

"More," he begged and Ratchet smiled through the haze of pleasure.

"Soon, my little Prime. Need to get you ready first... Let me add one more finger, stretchyou more."

Optimus nodded and released Ratchet's hand.

The medic traced a third, soon to be added, finger over the edge of Optimus' valve gathering beads of lubricant. And then, not fully withdrawing the previous two fingers, slipped in the third alongside.

Only when he started to push in deeper did Optimus react.

"Ah... Hurts."

Ratchet stopped but didn't withdrew his fingers. "Relax," he said gently and let his field concentrate around his fingers, the energy of it pulsing, undulating over the surface of his fingers relaxing and caressing the tight walls.

"It's tingling." Optimus squirmed but pushed down on the finger joints sliding through the opening.

Ratchet resumed the gentle movements of his hand. "It's my field, you'll learn to use it one day. You need to be stretched to take my spike." He spread his fingers gently, Optimus whimpering nervously. "Relax, Starling, I'm doing it so it won't hurt later."

"Starling... That'sa pretty name." Optimus smiled and gasped.

"Mmm it was very popular endearment back in my time." Ratchet felt Optimus relaxing slowly. Diversion worked, though he would have to remember to try to rewrite this ease in being distracted. "Can you feel the slide of my fingers? As it sets off your sensors?" He needed Optimus to concentrate on that, on the pleasure again. He gripped Optimus hand and licked long and hard over the palm. The reaction was instantaneous.

The young prime cried out, nervousness in his field burned up by the sudden explosion of heat and desire.

"Yes just like that." The medic encouraged and nibbled on the wrist.

Optimus gasped and his valve squeezed on Ratchet's fingers. Pressure sensors set off as charge tingled along his fingers, his spike jumping as Optimus cried out.

"Please," the young Prime whimpered. He looked at Ratchet, who pumped his hand into the valve, the other tracing patterns on Optimus' palm.

Ratchet lifted Optimus' hand to his lips again and licked one finger after another, his optics boring into Optimus' as he followed up by sucking them inside his mouth.

Ecstasy rippled along Optimus' circuits , connection sending feedback to Ratchet. A flood of bliss heated up his own circuits. He moved his hand, spike pressurizing fully as his fingers kept gliding in the warm opening.

"Soon."

By the time he withdrew his fingers Optimus was moaning and thrashing his head, hips undulating in want and need, valve completely relaxed, pliant and dripping with lubricant.

Withdrawing the stimulation made Optimus whine in loss.

Ratchet let himself enjoy the picture. It burned into his memory forever, along with the feelings branding his spark with a mark, that he declined to acknowledge just then.

He wiped his fingers over his spike, covering it in thin lubricant.

"Now..." He leaned forward, brushing his lips over Optimus' parted ones. The young Prime whimpered and pulled him down into a searing kiss.

Ratchet shuddered.

He positioned his spike against the valve, making Optimus moan, and pushed. The Prime rocked his hips in abandon onto him, taking his spike deeper, gasping and keening.

The head pushed through, and with a loud cry Optimus gripped Ratchet's aft and pulled him down, his spike sliding inside all the way.

Sudden heat and pulsing tightness turned whatever Ratchet wanted to say into a helpless moan.

"Slow down... Oh please, slow down."

"Nnngh deep, so deep," Optimus chanted. Ratchet dug his hands into young Prime's hips keeping, or trying to keep, him still.

"Yes... Oh Primus, yes, Optimus, I'm inside you, just let yourself get ready."

"More," Optimus demanded and with one hand pulled Ratchet's head close kissing him deeply with wanton abandon.

Ratchet moaned and his hips snapped forward on their own accord.

Optimus' torso arched off the berth and he tried to rock his hips onto Ratchet's cord. "Please move, Ratchet, please," he begged, and Ratchet did.

He rocked into Optimus, each movement eliciting yet another sound, each louder than the previous one. Until they faded into needy groans.

Optimus hands were lost on the expanse of Ratchet's back.

It was difficult to kept his movements even, as now Ratchet was propped on his hands either side of Optimus' thrashing head. The mind he was connected to swept him away with wave after wave of bliss.

But the steady, too slow, peace, was not getting him any closer to the edge, merely dragging along the processor-shattering pleasure.

He needed control back now.

"Open your spark," Ratchet managed, and flared his field at the first signs of fear. "I need to touch your spark. Trust me." He could open the spark via the connection but he wanted Optimus' trust, his own will.

Optimus looked into his optics, fear visible, but his chest plates slipped open, the white light of a mature yet not-yet imprinted spark shining through the crystal casing. A blissful haze lifted from his processor.

Ratchet pressed a hand to the casing, flaring his field from it, making Optimus arch into the ghostly caress. He sped up his movements, field flaring and withdrawing with the same rhythm as Optimus was suddenly swept away with pleasure again, steadily climbing towards overload.

With one hand on Optimus' spark, he hugged the young Prime and braced both of them for the final step.

He deployed a connection spike on his cord and his fingers, the sharp plugs ripping through the seals and connecting.

A brief flare of pain, Optimus' optics snapping open in surprise and fear.

Then Ratchet sent a heavy pulse through the connection, and pleasure-laced data through his spike. Optimus screamed as pleasure overrode everything: pain, fear, surprise.

The completed circuit made Ratchet feel the overload flash through both of their bodies, sparks reaching, fields flaring, entangling and vibrating together, his hand hurting as spark data flowed through.

Their circuits discharged until finally Optimus' valve clamped over his spike and he shot the transfluid, his data-spike withdrawing, the charged fluid soothing away any lingering pain.

The Prime slipped offline. With the last of his strength, the medic re-arranged the cabling, and released the spark. He withdrew his hand, numb with energy discharge, circuits surely burned. He cradled the young mech to his chassis, cycling his systems cooler.

He reviewed the data-packet unpacking in Optimus. Routines over subroutines of useful things, weapon specs, mods and software, everything installing seamlessly.

But what he couldn't check was how the imprint had gone. He could only see the personality matrix running.

This young Prime, he needed to be strong and just, and Ratchet made sure to preserve the trust.

Prime needed to love his people, he needed confidence and a level-headed approach. A perfect ruler. Ratchet also tried to enhance his humility to balance the confidence.

Whatever the personality matrix decided to apply and how... It was beyond him now, and depended on what manner of mech Optimus already was. Even the most experienced implanter couldn't make a strong mech out of the weak-sparked.

Optimus' spark was strong, the overload burning out all sensors in his hand. The spark connectors weren't supposed to be used during overload, but like that it was way more pleasurable and far less traumatic.

It was a different mech who woke up in his arms. Mature, fully adult, his optics regarding Ratchet with thoughtfulness.

"Thank you." He hugged the medic, and relaxed when Ratchet tightened his embrace.

"Forgive me for the pain, little Prime." Ratchet looked at the mech.

Optimus' field flared with affection at the endearment. "I trusted you, I still do. You did what was needed."

Ratchet kissed Optimus' forehead in parting, and disconnected them.

Optimus keened and pulled him close. Ratchet was suddenly grateful for the comfort after the disconnection which had left him feeling cold and alone.

"I want you," Optimus whispered, not a sliver of uncertainty in his voice. "Your fields over me."

Ratchet extended his field and enveloped young Prime within it.

Brought back from memories he sighed as his spark swelled with love. Optimus had been the last to be imprinted by him. After the young mech first left, he came back time and time again, and with time Ratchet had to acknowledge that whatever he felt for the young Prime was more than just a feeling to him.

With time he also learned that his spark had been bound to Optimus that day.

They were both different mechs now. Changed by war, by Earth... yet their sparks still resonated. Optimus was no longer a young Prime and Ratchet no longer Imprinter. Their bonds hardened and changed with time; from mentor and pupil to brothers in arms and lovers.