Passage: Attempting to bolster the North's defenses in "Dragonstone", Jon is frustrated when his authority is undermined by Sansa, who does not want him to repeat the mistakes that got their father Ned and brother Robb killed. Jon dismisses a message from Cersei Lannister that he swear his allegiance to her. In "Stormborn", he receives an invitation to Dragonstone from Tyrion, on Daenerys Targaryen's behalf. Subsequently, receiving a message from Sam that a hoard of obsidian lies beneath the ancient Targaryen castle, Jon decides to meet Daenerys, leaving a surprised Sansa as his regent. At Dragonstone, he declines swearing fealty to Daenerys in "The Queen's Justice" and instead asks for her assistance fighting the White Walkers. She demurs but permits him to mine the obsidian. In "Eastwatch", Daenerys is surprised when her dragon Drogon approaches Jon and allows the King in the North to pet him. Determined to convince Cersei that their true enemy is the army of the dead, Jon leads an expedition north of the Wall to capture a wight and bring it south to King's Landing. They manage to do so in "Beyond the Wall" but are surrounded by a horde of the Night King's minions. Daenerys arrives with her dragons, but the Night King kills one of them with an ice spear, forcing the others to flee without Jon. He is saved by the reappearance of his uncle Benjen, who is overtaken by the dead as Jon escapes back to the Wall. Daenerys vows to fight the White Walkers with Jon, and he agrees to swear fealty to her as his queen. In "The Dragon and the Wolf", the two negotiate a truce with Cersei, who agrees to join them in fighting the Night King's forces. Samwell Tarly learns that Jon was born Aegon Targaryen, the legitimate son and heir of Daenerys' brother Rhaegar Targaryen and Lyanna Stark. Meanwhile, Jon and Daenerys finally give in to their growing feelings for each other and have sex, unaware that they are related by blood.

Question: Who invites him to Dragonstone on behalf of the Targaryen girl?
Tyrion