It was Agatha all along...

I guess my main questions would be:
So Billy, at the moment of mama Wanda blowing up the hex and erasing her children, used his powers to 'warp' into another nearby Billy who had just died...but how would Toby, errr Tommy, be able to replicate that?? I'm sure there is less of a 'logical' explanation for how Wanda decided to scour the multi-verse for the kids...instead of sensing her son in another person--like a few miles away...
I got the impression the soul/essence/whatever was released and bound to the first host it found, so to speak. I didn't think it was intentional, but it's possible I didn't catch something


Also the loud, confident "Toby!" killed me