When Ongrow was young, his parents were put down after they had attacked a few other people. After they had attacked and were put down, Ongrow was adopted by a mean owner and his siblings along with him. As they were adopted, they were put in cages filled with big cats.
All of them were male, some female, but afore (Ongrow's sister) got raped by one. Then after they had all escaped, they had been adopted by Gabe, archer and asriel. Then they were told to attend the Panthera universe, but it didn't go well.
They were bullied over there as well. People tripped Ongrow, they took his belongings and they also close the doors on his tail.
They claim him and his siblings clumsy until he had been kidnapped by a gang of reptiles. Then he was raped by them as well and somewhat escaped.
Then to this day foward, he suffers from PTSD and stays in the shadows.