Shapeshifter, Caustic has a humanoid form though he considers it not very convenient (he uses the humanoid form for cases when he needs to speak, at least)
That is an active, attentive, fast and agile, rather wild one. Caustic is able to feel electricity of other beings, by his antennas on the body. It gives him an extra sense (that is useful, especially when visibility and other senses are limited). The bubbles on his body surface are ends of acid producing organs inside. By increasing inner air pressure Caustic is able to force the bubbles to explode. He can do so for attacking / distracting an opponent, but as the last way of action, in case if Caustic was cornered.