Generally speaking, Dungeons & Dragons - or any other form of tabletop role-playing game - would not be to Tyson’s tastes. It’s too much of a time commitment to work around his schedule and involves being far more social than Tyson is comfortable with most of the time.
However, though she abandoned becoming a therapist, Jasmine still knows the tricks of the trade and suggested D&D to help Tyson and Jethro talk about things that could not be confronted directly without incriminating either one.
For example: knowing that his brother works for a criminal and wanting to express concern about recent events doesn’t mean that Jethro can bring the subject up without forcing Tyson to either lie or incriminate himself in such a way that Jethro would be obligated to arrest his own brother.
Jasmine a system to talk around the problem, whilst actually getting the answers they both need. Jethro and Tyson play D&D together, with Jethro as the Dungeon Master where they’re mostly using homebrew, playing fast and loose with home rules, and mostly having fun telling a story together.
At any point during that session, either of them can use a code-word decided ahead of time. For the remainder of that scene, whatever scenario is unfolding, they stop playing the characters and respond as themselves.
So, if the first line Jethro gives a shopkeeper when Tyson’s character enters is ‘Welcome, we’re having a sale on pineapples’, then Tyson stops responding as Tzadok and beings responding as himself with the artificial separation of using a different name.
That way, Jethro can ask questions about Tzadok’s criminal activities - without them needing to line up with events that happened to that character - and Tyson can - in a purely fictional way that has no bearing on reality at all - tell his brother the truth.
It is a flimsy line of plausible deniability, but it’s enough to give them both peace of mind without having to openly acknowledge anything that had been said once they wrap up the game for that evening; whilst also providing a framework for them to have fun together, and purposefully make decisions to mess with the other.