In the first pic? that’s her tongue. She doesn’t know how to handle such a long tongue and it doesn’t help that horns were also growing out of her head and her tail became deformed and growing wings is probably painful. Not to mention that her fangs coming in caused her mouth to get pretty bloody.

She was just in agony in general.

But being a succubus has its benefits.

Like aphrodisiacs in your saliva and breath in general.