Reasonable and quiet with a strong moral code-- Lawful Good alignment. Seemingly biding her time as Eaglestar runs his last life short. Former rogue. Currently planning his assassination covertly, and in the nursery of all places, so that the rest of Forestclan will not refuse her leadership or kill her before she could reach the Starspring. (Or kill Hollytooth and her kits in revenge... of course a subtle assassination will be best.)

The assassination is also covert because Pine doesn't really trust Starclan to approve of the assassination either, partially because she grew up as a rogue until 8 moons and partially because Starclan granted Eagle his lives, even when he was obviously unworthy of leadership. He hadn't even had an apprentice by then. At this point, to Pine, Starclan is not a guiding or helpful force, but as a strict enforcer of the Code, which gets in the way of her killing Eagle and starting to heal her Clan. 

Pineleg was taken in by Forestclan as a kit, at the end of Kitestar's rule, just before Elmstar took over and created an atmosphere of fear for former rogues. She was good friends with Eagle and his siblings Fennelbelly  and Swiftscar as apprentices, but she was mostly Eagle's friend. He didn't care about her  not being born in the clan back then. By the time Eagle truly believed his father's bigotry about rogue-born cats, he had selectively forgotten about Pine's origins. Eagle and Pine shared the ambition, drive, and desire to see Forestclan better itself. Their friendship lasted through Elm's abuse, Swift's exile, and Eagle becoming leader too early, but was finally destroyed when Eagle killed Shinepool and Pineleg had to watch as the cat she used to consider her best friend acted so cruelly without second thought. Even his banning of allowing rogues and loners into the clan didn't change her feelings about him. She'd seen  the signs of his changing, yes, but never had to truly face his unbridled  cruelty like that before. She started the plot to kill Eagle the day after Shine's assassination, finally fully agreeing with her other friends Sparrow and Briar that something had to be done before Eagle doomed the whole clan.

Mate of Hollytooth. Mother of Skykit and Pebblekit. Close friends with Sparrownose, Briarcloud, and Birchleaf. Hollytooth is also a rogue-born cat, older than Pine. The two bonded and fell in love in the midst of harassment, bullying, and too-high expectations from their "pure" Clanmates during Elmstar's rule.