Karla is thin, though seems to be somewhat muscular from having been working day and night to escape the island. She has a light tan complexion, and long, unkempt ginger hair with a small ponytail in the back. She's seen wearing a white t-shirt and a pair of blue-gray shorts, both articles dirty, as well as white sandals with blue circles on the toe straps.
Karla is quite friendly, caring, and is willing to help almost anyone. She cares for her sister greatly, similar to the care and love the Bears show for each other. When she and Dave first rescued the Cubs in "The Island", Karla was quick to ask them if they were alright and to offer them to stay with her and Dave, acting like a motherly figure for them.
She doesn't have any interest for Dave, despite Dave having had a delusional crush on her very quickly after the two had first gotten stranded together. Karla didn't take it very well finding out Dave had purposefully kept the two stranded so he could romantically advance on her, angrily calling him out on this demented scheme. After finding out Dave's scheme, she and the Cubs used another raft near the surface to escape the island, leaving him behind.
Karla had a pretty awkward relationship with Dave, having little to no interest in him. However, Dave often cares about Karla to the point of being obsessed with her: sabotaging the baby bears and leaving them to die in quicksand; writing schemes and plans to eliminate everyone that stands between them and marry Karla. She eventually finds out and becomes disgusted with him, and willingly leaves him behind while she and the Baby Bears escape the island.
Karla helped the cubs when they were about to sink on a quicksand trap they went through. She and the cubs immediately bond while Dave remains aloof and uninterested. Karla sang a song for the cubs and talks about her close relationship with her sister.
- Karla makes it clear that she loves and misses her sister very much, as her motivation of getting off the island is to go home and see her again.