Jeremy Renner
Jeremy RennerReuters

Fans of "Agents of SHIELD" will have something to look forward to in the second half of the season, as speculations are rife that an original Avenger might be featured during the much-awaited "Agents of SHIELD"-"Avengers: Age of Ultron" crossover.

The news of a crossover was confirmed on 9 December when executive producer Jed Whedon told Entertainment Weekly: "You should expect something. The Avengers is the big tent that all the franchises play under. Obviously, we're included in that."

While it is too soon to say which main "Avenger" character will be gracing the small screen, bets are on Jeremy Renner's Hawkeye. This speculation further gained traction after SHIELD leading man Clark Gregg posted on Facebook an illustration of Hawkeye and Coulson. The illustration was without a caption and this had fans guessing about its purpose.

Secondly, Renner himself said previously that he would love to guest-star in the series if given an opportunity.

Here is what he said during a Reddit AMA: "I suppose if it was offered up, there's an outside chance it could happen. haven't seen the show, so I don't know how it works, but I'm sure the folks at Marvel have ideas, and when they're strong enough, they'll bring 'em to me. But I love me some Clark Gregg, he's so great. We killed him and brought him back to life to do 'Agents of SHIELD,' he's so good!"

Meanwhile another link that binds Hawkeye and "Agents of SHIELD" is Mockingbird, the character played by Adrianne Palicki.

It is not immediately known at which stage Hawkeye and Mockingbird's relationship is – they could either be starting their romance or she could already by divorced from Hawkeye -- but his introduction is sure to ignite the sparks of jealousy in Hunter.

Palicki recently told Zap2it that she would like to explore the relationship between her character and Hawkeye. "The interesting thing is her relationship with Hawkeye did happen. It's a big part of the character. I'm interested to see if that ever comes up or is brought to light or is mentioned in the future."