When is a fun little teaser something more? When it's Robert Downey Jr. and Nathan Fillion cross-promoting the upcoming Marvel superhero flick The Avengers and ABC's cop drama Castle. Why are these two rakishly handsome fellows chatting about their respective starring vehicles? Well, why not, some might ask. But the blogosphere is searching for deeper meaning in this commercial, even though Marvel's not throwing anyone a bone just yet. Fanboys are speculating that the spot means Fillion will make a cameo in The Avengers as Ant-Man on the way to headlining that still-gestating movie. (It's been rumored for at least a couple of years that Fillion would take that role, and Marvel flicks now routinely toss in a new hero at the end of each blockbuster to set up the next one.) Fillion has had a long and successful relationship with Avengers director Joss Whedon that includes cult favorites Firefly and Dr. Horrible's Sing-Along Blog. And Disney owns both ABC and Marvel now. Why not close this whole synergistic money-minting loop? It could happen. Even if it doesn't, it's cool to see Downey and Fillion kidding around with each other. More, please!