Long time lurker, first time poster - because boardgames :-D
I second Survive: Escape from Atlantis as a really fun light game, though if your brother enjoys Exploding Kittens then Fluxx might be a good option - there's even Firefly Fluxx!
Other recommendations:
Sheriff of Nottingham - a really great interactive bluffing game that usually includes a lot of banter. You score points by selling legal goods in Nottingham, or possibly by smuggling in contraband... if you can get it past the Sheriff, that is.
Batman Love Letter - my favourite of all the Love Letters. For one thing it has bat tokens, and for another we always do the deep voiced "I am Batman!" thing whenever we play the batman card and guess correctly. Who doesn't love that.
Clank! - a deck-building boardgame involving treasure-stealing and dragon attacks. It also has some push your luck and take that elements to it. If you pick this one up, I highly recommend playing with the companion app that adds in just a little more randomness to each game. There's also an expansion for it called Sunken Treasures.
Deep Sea Adventure - a small push your luck game where players are divers who have to go down and bring back treasure to the submarine. The trouble is, as soon as a player picks up a treasure, they start to use up the oxygen supply and, if it runs out while you're still in the water, you die and lose all your own treasure... so do you roll the die just once more to go that little bit deeper and maybe pick up a higher value treasure, or do you turn around and start booking it for submarine while you can...
River Dragons - such a cute light programming game where you're trying to get your villager across the water and to their home village. And before the "cute" puts you off, I've played this with quite a few guys who have really enjoyed it. You can steal other player's planks, you can make them jump in the water, you can block a player from playing one of their cards.. it's cute but can get kinda nasty.
Also, if your brother likes Terry Pratchett books, then Discworld: Ankh-Morpork is a good area control game.
Also also, an expansion for Potion Explosion (The Fifth Ingredient) has been released if your brother doesn't own it already.