Derek lost his father at a young age; it was what pushed him to become a doctor. No one should have to go through what he went through, not if he could help it. So he enrolled in med school and worked his butt off to earn his medical license. Afterwards, he lucked into finding a place at Hope Hospital. There he worked underneath one of the greatest doctors he'd ever met, a role model for the rest of his life, Greg Kasal.

After his father's death, Derek's mother dated a few men but none of them ever met Derek. And none of them ever would; not until she had a ring on her finger. But after several failed relationships Derek's mother realized that no one would ever make her feel the way her first husband had and gave up on finding someone new. Sometimes, on particularly nostalgic nights, Derek would wonder what it would have been like had his mother remarried. Maybe then he would have had a father figure, especially during his teenage years.

But anything was better late than never. A few months into his residency at Hope, Derek found that the father figure he'd always wanted was right there in front of him.

It was yet another long, busy day at Hope Hospital and Derek Stiles was about to lose it. There were so many things to do and the more time he spent shadowing the other doctors the dumber he felt. The other doctors didn't have problems comforting patients or performing surgeries. How would he ever know all they knew? How would he ever amass as much skill as they had? He could barely keep up as-is, and he wasn't even doing anything!

"Maybe I should just—"

"I hope you weren't about to say 'quit'."

Stepping into the break room from the hall, Dr. Kasal smiled wryly at Derek who stared at him, mouth agape.

"Dr. Kasal! I… I wasn't… I mean—" Derek sputtered, trying to find the right words, but when Dr. Kasal's smile disappeared Derek shut his mouth.

"The pressures of residency getting to you?"

Derek nodded dumbly, wondering how Dr. Kasal knew.

"I've been there."

"You have?" Derek asked incredulously. "But—but you're so skilled. I mean… You probably just picked up a scalpel and knew what to do." Apparently this was funny, because Dr. Kasal wasted no time laughing at him.

"I'm flattered, but no. I had to go through medical school and residency just like you. And let me tell you, there was more than one time that the workload nearly crushed me."

"How did you do it? How did you get past the stress?"

"Well, I had a bet going with my brother that if either of us dropped out of college or if I gave up during my residency the loser would have to pay the winner fifty bucks." He smirked seeing Derek's bewildered look. "I'm kidding—that's not why I stuck it through. I just did; it's what I wanted to do so I didn't let myself give up. Don't you want to practice medicine?"

"I don't know anymore! I—I wanted to be a doctor since I was a kid, but it's so much work. I…" Derek trailed off, his breathing growing heavier, his eyes pricking with tears. He started sobbing, his gaze going to the floor as he forced out the last bit of what he had to say. "I don't think I can do it." There. He said it. After all of his hard work, his dedication, Derek Stiles was admitting defeat.

He didn't dare look up, afraid to see the disgust on Dr. Kasal's face, but had he looked up he would've seen the opposite—he would have seen the surprise and worry in the elder surgeon's eyes.

"Derek, look at me."

Derek didn't. Sighing, Dr. Kasal closed the space between them and grabbed Derek by the ears, forcing the young man to look up at him.

"Dr. Kasal, what are you—"

"I refuse to talk to someone who won't look me in the eye," Dr. Kasal answered simply, his hands moving down to Derek's shoulders, gripping them tightly. "And you listen here: Out of all of the residents I've seen, few of them have been as passionate as you. You're a good kid, and I'd like to keep working with you so that you can become the doctor you've said you wanted to be. Now, you can go ahead and quit, or you can work past your problems and do what you came here to do. It's your decision."

Sniffling, Derek nodded. "I-I'm sorry Dr. Kasal… I shouldn't be complaining when I asked for this." He worked on straightening himself as Dr. Kasal's arms dropped to his sides, a smile slowly spreading across his face.

"We all have our moments. So, are you coming back to work or what?"

"Yes—I just, I think I needed that."

"Hey, it's part of my job to encourage the residents and keep the spirits high. Now go wash your face and meet me in the O.R. in two hours; I want you to assist me in surgery."

Guilt blossomed in Derek's chest whenever he recalled that day, as it reminded him of all the times he hadn't thanked Dr. Kasal. Derek had never fully expressed his feelings of gratitude or admiration to him. He might have been Derek's one and only father figure since his real father's death, but as far as Dr. Kasal was concerned Derek saw him as a mentor and nothing more.

That had to change. Ever since Derek heard that Dr. Kasal was infected with GUILT, he knew that if he didn't tell Dr. Kasal what he thought of him he might never have the chance. But fear stopped him; Derek could barely bring himself to visit Dr. Kasal before the operation. He couldn't bear to watch another father of his die. And what if Dr. Kasal was somehow offended by his confession? Derek hated himself for expressing such cowardice.

But now Dr. Kasal was okay. He'd survived the operation and in the past week showed a steady recovery. It wouldn't be too long before he could go back to living like he used to, before GUILT.

I have to do it now. If I don't then I never will.

His eyes fell to his hand, which held the doorknob in a white knuckled grip. He didn't turn it. "Come on Stiles, what are you waiting for? Just do it. If he's asleep you can just come again later. You have to visit him anyway. You're his doctor!" He argued with himself a bit more before finally opening the door. Once inside his legs suddenly anchored to the ground, leaving him rooted in the doorway.

Just a few feet away from him was the still form of Dr. Kasal, who in all likelihood was enjoying a much needed nap. Derek groaned. He wouldn't ever have this much courage again, that he knew. No matter how much Derek didn't want to do it, he had to wake Dr. Kasal.

He checked the hallway for any possible witnesses before shutting the door behind him. Every step he took towards Dr. Kasal's bed the heavier his body felt, but Derek pushed through the fear and anxiety and reached his bedside. This is what I want—no, need to do, so I'm not going to let myself turn back now.

A surge of confidence erupted inside of Derek. He grabbed Dr. Kasal's shoulder and shook it gently at first, then a little harder. "Dr. Kasal… Dr. Kasal, please wake up… Dr. Kasal, it's me, Derek!"

"Derek?" Groaning, Dr. Kasal opened his eyes, squinting them as they adjusted to the light. Derek pulled his hand away, smiling guiltily as the elder surgeon scowled at him. "Please tell me I'm dreaming. Please."

"Sorry Dr. Kasal. I would have come back later, but I really need to talk to you."

"It's that important, huh?" Dr. Kasal sighed and pushed himself up. Derek grabbed the pillow behind him and adjusted so it supported his back. "Thanks. So, what's on your mind?"

"I just wanted to tell you thank you, and I'm sorry."

"Thank me? For what? Better yet, what are you apologizing for?" Dr. Kasal kept his tone light but worry lined his eyes.

"I'm thanking you for everything you've done for me. You've encouraged me to do my best since day one, and if it weren't for you—had you not said what you did that day, I would've quit before my first year of residency was even half over… You told me that I had more passion than the other residents and said you wanted to help me become the doctor I wanted to be, and I—I'm…"

Derek trailed off, taking a few moments to calm his breathing and wipe his teary eyes before picking up where he left off.

"And I'm so proud to have learned from you, and I'm apologizing for not telling you how important you are to me sooner."

"Derek, I—"

"I'm not done yet." Derek spoke quicker now, struggling to get the rest of his message out before sobs racked his body and rendered him unable to speak. "When my father died, I-I didn't have anyone but my mother. I never did have a father to look up to, since my mom never remarried… but, Dr. Kasal, I want you to know that you're the closest thing I've ever had to a father and I'm so glad that you're okay. I don't think I could've lived with myself had you… had you—"

He wanted to say 'died', but the gravity of the word was too much for Derek to bear. Sobs racked his body, his entire being trembling before the one man capable of filling the gaping hole caused by Isaac Stiles' death. Too ashamed to meet Dr. Kasal's eyes, Derek stared at his feet, trying desperately to regain his composure.

"I-I'm sorry, I shouldn't be—hic—crying like this w-when I'm supposed to be a full-fledged doctor." He fought to chuckle, his breath catching in his throat and making it hard to breathe, the pressure in his chest only ever increasing. Derek couldn't hear anything over his sobs; could he, he would have heard creaking and the small grunt that accompanied it.

"Derek, look at me."

Two hands grabbed Derek by the ears, forcing him to look Dr. Kasal in the eyes. At first Derek thought that his eyes were fooling him, his own tears obscuring his vision, but then it dawned on him—Dr. Kasal was tearing up.

"I am so proud of you and I am honored that you think so highly of me. Thank YOU for never quitting, making all my efforts to help you worth it, and thank you for saving my life."

With that, the two embraced, Derek burying his face in the elder surgeon's shoulder, thanking him profusely for everything he'd done. Dr. Kasal listened, fighting to keep his own emotions in check as he comforted Derek, who Dr. Kasal would always have a special place for in his heart, a place set aside for his prodigy, a boy who he considered family.

A/N: I've always thought that Greg and Derek had a father/son thing going on. From what I remember from UTK, I'm assuming that Greg took care of Derek a lot during his residency. And since Derek's father is dead I think Greg would be a great father figure for him.

Also, I called Greg "Dr. Kasal" in this because although it's written in 3rd person, it leans a bit more towards Derek's POV.