Tuan Hoang was one of a group of tabletop-gaming nerds (with Mosstyn Corkindale (Corky) and Blossom Cooper) at Griswald's Grammar School who Shauna Wickle briefly hung out with when her friends were in a hypnotic spell caused by mysterious classmate Lem (in "The Case of the Lonely One"); she was seeking to get their assistance solving the case, though they distrusted her because they knew she would return to her own friends and stop hanging with the nerds once the spell was broken. At the end of that case, his mother took him out of the school (or he was kicked out of the school for kicking the headmaster, as he now claims), and he wasn't seen again until he resurfaced at space camp during the "Space Is The Place" story. He is skilled at using a Keysword.
Tuan will sometimes go along for a while with whatever his peer group is doing, even if it isn't very good; he went along with Blossom in attempting to corner Shauna to be hypnotized by Lem, though thought better of it and turned away at the end. At the space camp, he sometimes seemed to be playing along with the creepy things the other boys at the camp were doing (such as a panty raid on the girls), but seemed to have some distaste about it.