MCU: 14 Things You Learn Rewatching Guardians Of The Galaxy
3. And He Is Finally Going To Fulfil His Promise To Ronan

Thanos makes a promise to Ronan in this movie: if the Accuser brings him the Orb, he'll destroy Xandar.
It's a promise Thanos is certainly capable of following through on if he gets his hands on the Power Stone and, although Ronan has betrayed him and the Mad Titan has no loyalty to him, he is still technically going to be fulfilling that promise in Infinity War.
Xandar is where the Orb is housed, and that means it's going to be one of Thanos' first targets before he heads to Earth. The trailers have already made it clear that he gets his hands on the Power Stone (and uses it), which means Thanos is going to brush Nova Corps aside and quite possibly Xandar with it. Just a shame Ronan isn't around to see it.
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