A moratorium is in effect on adding information from Fire and Blood until December 20th.
From A Wiki of Ice and Fire
|Spouse||Lady Lanna Lannister|
A Clash of Kings (mentioned)|
A Storm of Swords (appendix)
A Feast for Crows (appears)
A Dance with Dragons (appendix)
Lord Jast owns black steel armor with three golden lion heads inlaid on the breastplate.