Chaltuu is just having a night stroll. She loves nighttime. Her nickname as a cub was "Owl" because she loathed the daytime. Not even like the thing where a lion will hunt in the early morning or later afternoon and nap during the hot part of the day. She despises sunlight and will only hunt or patrol her territory borders when she can't see the sun anymore, or can only see a little, tiny part of it. As a cub Chaltuu would always sleep during the day and come out when it was dark. Probably because most of the lions would be asleep then or not notice her. That's another reason why she never became social. She'd never play with them because she was always in the cave during daylight.
Yes, I know lions are nocturnal, I should have put this here before. Anyway, I know lions are nocturnal, but my point was that Chaltuu refuses to go outside if it's daytime. The only picture where she was in the day was "Those First Scars" and that's because she was beaten in the cave and stumbled out and stuff.