Lucy breathed hard from exhaustion both from her depleted magic and from the bombs Jackel threw at her. To her the exhaustion was worth saving her friends...even sacrificing her first friend and key Aquarius. Around her Alegria was disintegrating, slowly releasing her guild and family.
She wanted to welcome her family back with a smile but the energy and effort it took to smile was too much for her already tired body. Even if she could manage to smile anything more- like crawling away from the red substance- would be way too much. Lucy was barely even staying conscious by sheer will alone, blood loss from Jackel's bombs not making her situation any better or easier.
Lucy's consciousness was slowly fading, faster than her will was strong. Her eyes were halfway shut, sounds of something ripping reached her ears. Her eyes opened a tiny bit when she heard that oh so familar voice shout her name in concern and worry. A smile touched her lips, mouthing the word: "Natsu..." in a whisper. His lower of half of his body getting closer to her.
The smile on Lucy's face grew when here friends stood before her to fight the remaining Tartaros members who she had merely knocked unconscious. It was during that time- when her friends backs were turned to her- Lucy's body began to glow a reddish color. By then she had fully lost consciousness, glowing body slowly fading from the battlefield. Nothing remained where she once was besides puddles and smears of blood.
-After the fight-
Natsu went back to where his best friend and partner lay regaining her energy and magic. When he reached the spot where her scent mainly lay he found the area empty. Minus her blood and scent. His eyebrows pulled together in confusion. Lucy's scent hadn't moved from the spot, and there was no other scent mixed in with hers that he could smell. Maybe Erza and Mira picked her up for treatment. She did have many open and bleeding wounds. Yeah, that's it! She's just healing with Wendy! Natsu convinced himself despite a part of him telling him that wasn't what had happened.
Footsteps reached Natsu's ears, heavy ones. Erza and Gray appeared behind him. Natsu turned to face them. "Aren't you supposed to be with Lucy, Erza?" Natsu asked. Erza's eyes widened. She had thought the blond would be with Natsu. Slowly Erza shook her head. "I thought she was with you, Natsu. If she's not with you then where is she?" Erza questioned aloud. "Do you think she's with Mira?" Gray piped up. Erzs shook her head again. "Mira is gathering her sister, and searching for Wendy. When I passed her told me to look for our team to make sure they were acounted for." Erza explained. Natsu's eyes widened, if no one has her than where did she go? Without waiting the pinkette dashed off to look for her.
The Fairy Tail guild spent days searching for their blond member. All of Fiore was searched in case she had somehow moved from the battlegrounds. They would come back to report to the master of their findings. Every location that turned up empty was marked off the map. So far over 90% of Fiore was marked off, at that point the Master Makarov doubted they would find Lucy. It was like she had disappeared into thin air.
A full month passed, the search for Lucy had long been called off once the whole of Fiore was covered in red X's. However that didn't stop the fire dragon slayer from searching. He never stopped looking for his partner, never stopped believing they could find her. No one could stop him from searching, no one even tried after Erza attempted to. If Erza couldn't stop him no one could.
Another month passed, still no Lucy. Now Natsu didn't even attempt to search. After last month past he had to come to terms he couldn't find her. Had to come to terms with her not even being on Earthland anymore. But he still held onto the hope of her coming back. Even as the days ticked by, he still hoped for her return. Not knowing it wasn't possible for her to come back. No one knew what she had sacrificed nor the after effects she took upon herself to save them. They would never know because no one -not even Lucy's spirits- could reach them.