Cat's cradle, huh? Really cute and original concept for a pic! These two do teamwork a lot, so they would probably do great at a game that requires them to both continue a pattern to win. I love how you draw hands--the poses of the fingers look very natural. Hawkeye's right leg could be shaded a bit brighter to show that his knee sticks out toward the viewer, but that's the only constructive critique I can offer. Your style's cute, and Hawkeye totally looks like Jeremy Renner.
Hawkeye's right knee looks kind of weird, but sortof gives the effect, and aren't black widow's hand a bit too big? On another hand, amazing job! The colouring is really good as well as the details.