Los Angeles: Actor Robert Downey Jr has welcomed Tom Hiddleston to Instagram with a post related to the "Thor" star's girlfriend Taylor Swift. Downey Jr posted a shot of Swift's beau from his Fourth of July vacation (during which he was clicked wearing a I heart T.S. tank top) and wrote a hilarious caption, reports eonline.com. "Join me in welcoming the biggest T. Stark fan of them all to Instagram!" Hiddleston recently joined the social media platform and posted his debut shot in his Marvel character Loki. "He's back," he wrote presumably from the set of "Thor: Ragnarok", currently shot in Australia. Hiddleston has already garnered almost a half of a million followers on Instagram.