Theta

When Theta was created, it was by the Alpha shedding his own ability to trust in the form of a childlike representation of the very concept of Trust. What may seem contradictory is how this actually makes Theta very timid, shy and hesitant to trust people without a lot of reassurance and build-up—but this is actually because of how much Alpha's trust in people had been shattered by the trauma he was enduring, something that was then reflected in Theta.

Theta starts out nervous with new people, having to be gently coaxed out of his shell (this is easier with a trusted person on hand, but not impossible without). As he relaxes, he becomes a very playful and curious sort, asking questions and enjoying trying to learn new things. There's a childish innocence about him, and a great deal of kindness, but he's still a military AI that helped his agent kill countless people in sometimes gruesome ways and was proud of himself for doing so, so there's a bit of an edge in there somewhere.

In his AI form, Theta is a holographic projection of a soldier in default Mark VI armour, coloured magenta and blue (or purple, depending). This form is small enough to sit in someone's hand and not solid.

In the human form he's been given in game, he's a young teenaged boy of average height for his age. He's white (with some freckles), has messy blonde hair that sometimes comes out curly, and has heterochromatic eyes of unnatural magenta and blue. He's physically rather weak, but can focus and make his body temporarily intangible to pass through objects.

In game, Theta has a human body. It's not a completely normal body, giving him several advantages that reflect his status as an AI, but also several drawbacks. He's physically weak, clumsy, prone to forgetting to eat and sleep, struggles with insomnia and is more prone to illness than children who've built up their immune system naturally.

Theta is capable of phasing through solid objects, with a great deal of concentration. This fails a lot more easily when Theta is stressed.

Theta processes things uncannily fast, handling things like mental math with impressive speed. He also notices small details and subtle motion much quicker than an ordinary human.

Theta is very nimble and good at dodging and blocking, keeping him safe from most physical harm.