Conjoined twins

Between their necks there is a small, almost tiny gap, where only the head of a small dog would fit.

They have one body and two arms. Martin controls the right side of the body, Matthew controls the left. They cannot playfully hit each other with their elbows or touch shoulders. If they play video games, they use a single joystick, with Martis controlling the movements and Matthew controlling the jumps and actions. They play as the same character. Their body is shared, so if, say, Matthew leans back, then so does Martin, and this should be marked like this: the twins' bodies leaned against the wall. They are 19 years old.

They are dicephalic parapagus twins: two heads on one body. Matthew and Martin are conjoined twins, fused at the chest and pelvis. This means they have two heads and one body. Each twin controls an arm and leg on a different side. For example, Matthew controls his left arm and leg, while Martin controls his right. Nevertheless, they have learned to coordinate their movements and, for example, use a phone in one hand.

They also share a common digestive, excretory, and circulatory system, but each has its own heart and brain. Their lungs are a different story: they are fused at the third lung, in the middle.

Despite their intimidating appearance, Martin and Matthew are kind and even playful. They aren't exactly academic nerds, but they're not exactly bad students either. It's fair to say that Matthew is more outgoing and talkative, playful and stubborn, while Martin is more calm and friendly, but also not averse to a bit of mischief. For clothing, they buy two identical T-shirts at the store, for example, and their mother then tailors them into one to fit the twins. They also share jeans, socks, and scarves.
Appearance: Both are single-celled conjoined twins, so they look identical. They have black hair and blue eyes. They most often wear a blue T-shirt. They have fair skin, a slender frame, and a slender, not overly long neck (like a normal person's).
Another important physiological feature of their twins is that they cannot separate and are always together. One twin cannot control the other's arm or leg. They can only cross their arms by the will of both, and even more so nudge each other with their elbows (they cannot)
Another very important thing!! The twins share a body with two arms and two legs. One twin controls one arm and leg, the other controls the other arm and leg. If Martin or Matthew need an arm or a leg from the other twin, they can ask for it. If someone leans back, the whole body leans back. They are dicephalic parapagus twins: two heads on one body. Signals from one side can produce sensations in the mid-section (sometimes even on the "other" half); the brothers sense each other's balance and muscle tension, thereby coordinating their movements; this is not an "exchange of thoughts," but rather the joint functioning of their nervous systems and a synchronization honed over years.