Cody Garbrandt and TJ Dillashaw have made it very clear over the past 6 months or so, that they truly do not like each other. The former Team Alpha Male teammates have had a very public beef, stemming from TJ leaving Team Alpha Male, and Cody assuming his role as hot-head-enforcer for TAM, made it very clear that TJ was in fact the "snake in the grass" that Conor McGregor had called him. After Cody defeated Dominick Cruz and became Bantamweight Champ, it was suspected he would fight TJ next, but Cody did offer a rematch to Dominick first, who declined, leaving TJ as the clear-cut challenger.
Now, add in the fact that these two have to spend months together coaching against one another on The Ultimate Fighter 25 - Redemption, there will surely be fireworks. The trailer for the next season of TUF dropped yesterday, and you can see there will be no short of drama, as the two trade verbal jabs, and possibly brawl (you can see Cody at the end of the trailer grabbing TJ by the throat, oh man this is gonna be fun).
As far as the fight itself, I was truly impressed by Cody in his fight against Dominick, and I think TJ is just a knock-off version of Dom, so I think Cody will be able to retain the belt, and hopefully via Knockout, because I know how badly he wants to put TJ away for good.