Breach is a member of the group simply known as "The Pack", one of Van Kleiss's personal goons who does his bidding. She is an EVO born of the event that released nanites into Earths atmosphere, infecting every living creature in it, and is in constant rivalry with Rex.
Breach has the power to open portals linking two different space at the same time. She mainly uses this ability to travel around, or for others to travel around. She also uses the portals to defend against attacks such as gun fire, and even throw the portals around like projectiles, removing any and all threats from her vicinity. She can keep the portals opened for however long she want, and make them however large she pleases.
Breach has an alternate dimension which she uses as her personal collection space. She has an entire city placed inside the dimension, meaning she could open portals as big to gobble up entire cities. Breach can see, hear and feel whatever that happens inside the dimension, as she reacted to Rex destroying her collection, by releasing him from this alternate dimension.
Breach is als currently the only EVO in existence besides Van Kleiss and Rex, as she took Van Kleiss and herself away in a portal, possible to the alternate dimension where she was safe from the wave Rex generated to cure all EVOs.