But he couldn't fight forever =)
As Asriel slipped into unconsciousness, he tried his best, but there was nothing he could do. Asriel lost his body, maybe for the last time. He was only in control of his mind now.
"That was pitiful." Flowey remarked, giving Asriel a smirk. "Poor Asriel, couldn't even beat his own self."
"You aren't me, Flowey." Asriel growled.
"Oh, but I am!" Flowey chuckled, pulling Asriel closer to him. "We're the same, you and me." "Think about it. I'm basically you, just, dead!"
Asriel attempted to hit Flowey, but his fist went through him.
"Asriel, don't you remember? We're inside your mind. You can't hurt ME!" Flowey grinned evilly. "But I can hurt YOU."
"That doesn't make any sense." Asriel remarked, frowning at the evil flower. "How does that work?"
"Like this." Flowey chuckled.
Asriel suddenly felt a sharp pain in his right leg.
"What the-?!" Asriel cried out. "What's going on?!"
"You forget, Asriel, that i'm in control of your body now." Flowey calmly explained. "You see, the body belongs to you. So if your body gets hurt, you get hurt." "But since i'm in control, it doesn't matter how much the body is hurt as long as your spirit is still alive. Your leg is painfully hurt now, but you can still walk normally, because, of course, i'm in control, and I don't feel your pain."
Asriel was silent. He knew why Flowey was hurting him. By hurting his spirit, he made it weaker. Flowey was speeding up the process of taking over Asriel's mind, as well as his body.
"You... w-won't get away with this..." Asriel said weakly.
"Oh, really?" Flowey made a pretend worried face, then laughed. "I doubt you really think that. You know that you are too weak to take your body back again, which means the only way to stop me is to kill me... and you." "You know Frisk can't kill me."
Asriel stood there, thinking about what to say.
"... It's true." He mumbled. "I can't stop you." "But I think... that Frisk can stop you... even if it means killing me."
"No you don't, Asriel."
Asriel felt more pain in his leg.
"You know Frisk can't do it." Flowey calmly stated.
"I... know... that Frisk can't do it..." Asriel mumbled, tears rolling down his face. His spirit was beginning to submit to Flowey.
"That's right, Asriel." Flowey smiled. "That's right."
"Asriel!" A voice echoed through Asriel's mind. "Asriel! I know you're in there!"
"Your friend is back." Flowey grinned. "Last time I fought them, I wasn't nearly as strong as now. You know that you have the human Souls, don't you, Asriel?"
"I didn't have much control over them until your mind began to submit to my rule as well." Flowey explained. "But now I can use them! All six human Souls, at my command... can you imagine just how great that is?"
Asriel was silent.
"Aw, too afraid to answer? I understand. I really am SCARY, aren't I?" Flowey chuckled. "Well, i'm going to kill your friend now~"
"You will NOT." Asriel growled.
"Oh, you still have some fight left in ya!" Flowey smiled. "I was hoping so. It was getting kind of boring without you saying anything."
"You will not kill Frisk." Asriel said again. "Frisk knows how to fight."
"But you forget, Asriel, that Frisk has always relied on their 'Determination'. I have pierced Frisk's memories as well, forcing them to give it up. They have no time to learn how to fight on their own, so of course, I will win." Flowey laughed. "Nothing will stop me now."
"Maybe Frisk can't stop you alone... but maybe... just maybe... I can help." The goat teenager looked Flowey in the eyes. "I can stop you if I try my best. You haven't corrupted my mind yet, Flowey. I can still slow you down, and then Frisk can kill you."
"Whatever." Flowey grinned.
"Asriel, where are you?" Frisk's voice came again.
"Excuse me while I kill your friend now." Flowey smirked. "Leave me alone for now, would you?"
Frisk stood there, calling Asriel's name. They knew he had to still be in there, because, earlier today, they had realized that they, Frisk, were not the only hope. Asriel was. Asriel had to be strong enough to stop killing. Frisk couldn't stop him, but maybe they could help.
"Asriel, please! I want to help you!" They called out.
Eventually, Asriel showed up, approaching Frisk slowly.
"Asriel!" Frisk called. "I know you're in there! You don't have to kill them!"
Asriel stopped moving.
"Who's Asriel?" He chuckled. "Never heard of him."
"Wha-..." Frisk opened their mouth to speak, then stopped. This was definitely not Asriel.
"Asriel, I know you're there. Fight! Fight whatever has happened to you!" Frisk encouraged. "You can do it! I know you can! You saved me when we battled last! You're a hero! You can do it!"
"I... c-can do it..." He mumbled.
"I can stop Flowey..."