Davos of House Seaworth might vouch for Gendry as the heir apparent to House Baratheon, seeing that he's witnessed Jon's ascension to King in the North and has befriended Gendry before. As former Hand of the King to Stannis, his word holds influence in the Stormlands. He might even convince Gendry to follow Jon's example and lead the Stormlands against the Lannisters.
