Xisuma is grians twin brother they are both avins but xisuma got there mothers voidwalker magic and some of that went to his wings making them different shades of purple and translate as for grians are normal and is red blue and yellow.
They lost there parents when they where 16 and got adopted by generik at 17. They both trained to be admins and grian went off to make his own server as for xisuma stayed on hermitcraft and took over for generik.
The twins didn't see each other untill season 6, when xisuma stepped out of the portal he got tackled to the ground knocking his helmet off and his wings to fluff up from the shock of being tackled.
When xisuma released what is going on he hugged grian tight and where happy to finally be reunion.
Keralis and mumbo on the where worried for a minute until they saw there boyfriends hug each other.
The twins explained to the others that grian is xisumas younger twin brother and everyone was shocked that there admin had a twin.
The sever was much more fun now grian was on it and he was able to get xisuma into alot of pranks that sometimes got the two in trouble with there boyfriends bit they always flyed away before that.
The few of them who were familiar with a helmet-less Xisuma took a while to get used to Grian. The wings are thankfully a give away, but their similarities still cause the occasional double take!
Xisuma seems so much more relaxed as a whole with Grian around. He wears his helmet less. A few hermits have even caught him relaxing in his base without his armour. The two share several inside jokes. Grian doubles over laughing when he hears Keralis's way of saying Xisuma's name - Grian and X have been mispronouncing each other's names on purpose for years!
Mumbo and Keralis also have a lot of catching up to do. Xisuma and Grian have always been quiet about their families. They knew their parents died when they were teenagers, and they knew an admin took them in (their opinions on the admin aside.) Even that information took a lot of trust.
Seeing their boyfriends so happy with his twin though... It's nice. Maybe they can go on double dates at some point.