Tam is a young Human male that you can meet right after you begin a new game, he is off to the left of the Ancient Statue to Braccus Rex.
When you engage Tam in conversation he will at first be distracted by a mirror he is holding, he will quickly realize you are talking to him and depending on what race you are may say something specific which in turn will allow you to respond with a special dialogue.
For Lizards and Elves he will say "I'm not supposed to talk to [insert race here]."
If you use the Elf dialogue he will say he was told that Elves eat people.
If you use the Lizard dialogue you can tell him Lizards are famous storytellers and proceed to tell him one of two stories. No matter which one you select he will become uncomfortable.
Tam asks if you are a sourcerer, you can say yes and you can also say he must be one too since he is here. He will make some small talk about how it is nicer out where he is than inside the fort.
If the PC (as Lohse) tells him to check with his mirror to see if she's a sourcerer, he becomes terrified and drops the mirror, then stops speaking to you. Speaking to him once more, he will say that she isn't a person; she's wearing a person. Then he runs away.
You can also ask where his parents are, he will tell you the magisters came to cure them, it is safe to assume they are already dead or Silent Monks.
You can finish talking to him about the Voidwoken attack and he'll mention how he isn't scared because everywhere can be scary, after that there isn't anything else to talk to him about.
He doesn't seem to be related to any quests or dialogue anywhere else in Fort Joy, but that could change, possibly could be revealed that one or two of the Silent Monks in the dungeon are his parents, who knows.