Triton

Lil' Triton Triton

Triton is the celestial war-horse empathically linked to Bing IronBlade.
Until Bing was reincarnated as a gnome, Triton took the form of a mighty purple war steed. Afterward, out of sympathy and necessity due to the diminuitive height of gnomes, Triton takes the form of Lil' Triton, a war pony, and still majestic in its own way.
Triton is a celestial angel that finds it amusing to answer the calls of mortals. Bing first called upon his celestial mount when he was a much younger man. Triton heard the call and took the form of a mighty war-steed.

Over the years, Triton has grown quite fond of Bing and has a high opinion of his character and shares his disdain for draconians. Also, Bing takes care to outfit Triton with the best barding money can buy (or at least on a Knight's salary), which delights Triton to no end.
In the War of the Lance, Bing suffered great injuries, limiting his mobility and his ability to easily mount the war-horse. If Bing was a lesser knight, Triton would stop answering the summonning calls, but as it is, Triton cares enough for Bing to kneel for mounts and dismounts.
Triton has never revealed his true nature to Bing, as is custom for these types of arrangements.