Sakay & Asika come from a world where chili peppers are even hotter and freakier than in ours : along with the burning sensation and hot peculiar feel, they can cause body modifications, give super powers and a lot of other weird stuff that can be more-or-less practical.
Think Devil Fruits from One Piece - Zoan, Logia or Paramecia, they all work; only:
-they don't come in one single exemplary, all sorts grow in great numbers everywhere and you can even cultivate it yourself (it's tough, tho)
-the effects don't last long, a whole body-affecting chili's effect can last 30 minutes, tops. Then again, you can eat multiple ones at the same time (we don't recommend that at all) or just a third of one, depending on your needs.
-they can taste bad, real bad. The freakier the effect, the greater the pain and the toll is likely to be. And it's not just the mouth, you can feel it in your whole body. Pro consumers train a lot and gradually try hotter peppers. His Tselatra's intensity is around 80,000 SHU and it comes with tingly sensations.
NOW! About this lad!
Like Sakay, Asika is a pikaroka, a professional pepper researcher. He joined her organization a couple of years after her arrival. He comes from a successful family of geniuses and prodigies. He is famed for his brilliant intellect and knowledge of peppers, he's not crazy over them but he finds them fascinating enough: their shapes, their variety, their effects, their history… he likes knowing and experimenting more.
Not the tasting, tho. He not very good that.
His parents are happy and proud but sometimes they worry for his safety. Sometimes, knowing Sakay is with him calms them and sometimes it does the opposite.
He's pretty content. She can be hard to manage at times but he finds it exciting to be with her too (don't tell her tho, it's embarrassing). He, too, opens up a lot when with her. She's like one of the only person that laughs at his jokes.
Asika isn't weak per say, his job and his team-up with Sakay keeps his body busy enough so he has some muscles. But it's not like he ever really wanted them or thinks much about using them so eh… it doesn't serve a whole lot and isn't super impressive.
He mainly battles with his mind, comes up with creative strategies and plans. However, usually, the thought of any effort (mental or physically) disdains him a bit. And getting hurt is bothersome. He'll be motivated to take action only if he sees an opportunity to experiment or learn something interesting or if Sakay is somehow involved in the matter (and it's serious).
Some other peppers he uses frequently
Tsoka - consumer's lungs become superhuman
Posaka - consumer's body breaks down easily, can be put back together
He doesn't have a lot of pepper he uses frequently, he can't handle them well anyway and doesn't feel like getting better at it. He'll bring along a batch of new not-too-hot peppers on each mission to try them out. He borrows some from Sakay to create combi attacks or just tells her how to use hers.