guy who exists is a user on social.targaryen.house. You can follow them or interact with them if you have an account anywhere in the fediverse.
I've gotten a lot of reports of not being able to log into various instances with Tusky. It's MEANT to be able to log into any instance, so it's not by design. It also seems for a given instance some users will be able to log in and others can't so it's not even necessarily an instance-dependent bug. Right now I know of one SSL-handshake related bug but I don't know for sure the login issues are all a single bug yet.
@Vavassor i was able to log in just fine with tusky so i dunno what's going on
