[quote=@Aqutanama]
I was thinking of having a really old guy like pushing 90-100. In his life, he was set up as a sniper or "ranger" back in his day. They were based on your smart applicants and patience ones. After that, he gets wounded and needs to take leave, honorable discharge. Probably got a medal or something. It could be a spinal injury, which caused paralysis from the waist down. After that point, he moved towards science in hopes of restoring his body and helping those like him make it through. Near the end of his life, he started to hate being alive. Always needing help when he was once strong enough to care for himself. That piled on with being crippled. In a sense, he gave into depression near the end. Could say that he was one of the benefactors who helped with the project or funded it, as he was looking for any way to fix himself. However, I would say that he wasn’t part of the project specifically and could have just been someone too close to the real experiment when it went off. To him or in his mind he died and was reborn into a youthful body. 
[/quote]

That makes total sense to me. There would have been a number of other research companies in the same facility, probably on one of the upper levels. The people responsible for the accident worked out of one of the basement floors. 

Did you give any thought as to what kind of life your host body had before your character wound up inside them? Athlete? Gladiator? Or some other idea of you own?