Insane summon who spent 999,999,999 years in isolation

However, there is one fate worse than all of that, one fate worse than living as a human, worse than anything I can imagine, but maybe I'm biassed. You see, I am a summon, a protector of these wretched human scumbags. But the life of a summon is most interesting when we fight, for the rest of the millennia we are kept in the same empty space, no contact, no walls, not even a floor. All so that I can die holding a sword for some wimp that can't even survive on his own or some noble shit who needs his hand held through a road trip. It doesn't matter what I do, how strong I am, how powerful… I always return to this forsaken void. Whatever twisted thing that made me created this space, so I could train, as a result the time is severely warped, even a few seconds out there takes a century to pass. I’ve been in here so long the internal monologue is just the latest addition to my insanity, to make matters worse the more insane I get the quicker people are to throw me back,
By my best guess this marks the