Looking for verification that Katy Perry and Orlando Bloom's new rumored romance is of the serious variety? Well, look no further. How does "quality time with his 5-year-old son" strike you as an emotional investment? Perry recently joined Bloom and son Flynn for an afternoon birthday party for Robert Downey Jr.'s son Exton in Malibu. "She looked very comfortable with Flynn, and they were both smiling and happy," a source tells E! News. "Flynn was having a great time and didn't want to leave the party. They stayed for several hours before they all headed back to Orlando's."

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On an only slightly related note, can you imagine how awesome your birthday parties would be if your dad was Iron Man? But anyway: One other source, at least, still isn't convinced about the budding romance, insisting that and time spent together for Perry and Bloom is strictly platonic. It's also worth noting, though, that this source also insists that Perry and John Mayer "are still very much together," so maybe it's just a delusional Mayer trying to change the narrative while staying off-the-record.