Essentially, the High Court is viewed as holding itself apart from contests that don't involve themselves or harm to their Court. Their ruler is the High Queen, Sorcha, The Unchanging Queen and Logic.
The High Court is emotionless and/or controlled. Members of the High Court don't live among mortals, but rather exist in the "otherworld" known as Faerie. They are practical to the extreme.
There's a book written by Sorcha, On Being: Faery Morality and Mortality. From this, it has been assumed her to be very philosophical. Sorcha sent her likeness to a number of Pre-Raphaelite paintings, particularly The Golden Stairs, from this, it has been assumed she likes art and/or artists.
It is revealed Sorcha and the High Court have a penchant for stealing Half-lings and Sighted Ones, a practice the Dark Court is aware of of. (Irial hides half-lings Ani, Tish & Rabbit from the High Court) It's not clear if the seasonal courts are unaware of the High Court steals/takes half-lings and/or Sighted Ones; or if they simply don't have any to hide; or both.