Though undeniably pervy, she is not in fact the most disturbing of Mutt's inc/succubus characters. (That distinction might currently go to Lewan). Ishtar is fairly good-natured, though she tries to hide it, and will usually take no for an answer, eventually.
Ishtar adopts the female pronoun and is usually seen in the form of a blonde woman, often with additions; tiny red devil horns, tail and bat wings seem to be a favourite.
She 'dresses' revealingly. She seldom wears actual clothes, just imitates them.
She prefers men to women, but this is in the sense of preferring a Wispa to an Aero; Ish likes anyone. (She also likes chocolate, and any combination of the above.)
She does not have any particular sexual habits or kinks, but likes to do whatever her chosen target or partner is into, with very few limits to what she will try.
These days Ishtar is almost always a non-lethal feeder, though she was not so in the past.
Ishtar is a decent shapeshifter - better than even an educated observer would think, considering she seldom does anything outwardly impressive. She can survive injury and stabbing up to being almost bisected. She is familiar with a number of species' physiologies, enough to appear to be a member of that species. She can also impersonate individuals. She can fake chemical 'tells', meaning she can impersonate someone even down to their smell, and emit pheromones with varying effects (though this isn't effective unless she is very familiar with the species of the person she's trying to affect).
She has a good memory for appearances, has very good spatial thinking (like all demons) and can carry more mass than she usually does. She is not bright, but pretends to be dumber than she is. That's why she is usually blonde.
Ishtar is experienced at staying alive. When defending herself she uses catfight techniques (hair-pulling, scratching and other dirty tactics). Sometimes she tries to take her opponents off guard by pretending to be really, really turned on by the fight.
She's psychologically unable to fake sexual interest in someone who really scares her.
Ishtar used to be a member of a succubus pack based in hell. The members were all female by preference and their prey was almost exclusively male. They named themselves after figures in Roman mythology; Ishtar was not called Ishtar back then. They were lethal feeders, sometimes leaving the prey alive only to chase him down afterwards and kill him.
When Ishtar hit the big 1-0-0-0 (years old), she abruptly left the pack, severed all ties and took to wandering the worlds. She does this with the aid of a key stolen from another demon, who was not best pleased.
Laatutakuu, the Countessa and Pasht and frequently goes nightclubbing with them.
She idly covets Suitov Iceheart (though is nervous of his familiar) and has impersonated him successfully once or twice, indicating that she has got close enough to get a read on his scent, pheromones, morphic signature, voice and mannerisms.
Weft, Katai and Zade don't register on her radar, though she will occasionally tease people she isn't otherwise interested in as a strategy to impress someone else. She is neutral towards Jaina. She is friendly with and interested in Lance, though they haven't happened to spend much time together yet. She has exchanged harsh words and blows with Serpy Lockfist, but likes him.
There have been rumours that Ishtar was at one time engaged to be married, and even set a wedding day. Apparently other circumstances - like, say, the destruction of the venue - forced the abandonment of this evil practical joke conspiracy before its conclusion.
Ishtar maintains a metaphorical 'voice' in her author's head, like most of Mutt's other longstanding characters, and occasionally likes to comment on Pro-ceedings.
Ishtar has been seen (OOCly/uncanonically) sublimating some of her frustration, sexual and otherwise, into 'creative' pursuits, including sculpture and fiction writing. Because her favourite writing topics are other fictional characters (so that in effect what she is writing is metafiction), and she is not shy about pairing them up in stupid combinations and writing ridiculous sex scenes (with no prejudice regarding the gender of the participants), this hobby has caused plenty of friction.
When Ishtar is being written on the boards by her own author instead of being left on the sidelines, she is seldom frustrated enough to write fiction - so that in effect it can become an unsubtle blackmail attempt, whose effectiveness depends whether Mutt's frame of mind is more 'blushing innocent' or 'college boy' at the time.