Any of these can take place during any point in the series, just let me know beforehand 

Scenario 1: The first time your OC meets their pairing, and Merlin activating Taro for the first time when he's created 

Scenario 2: Your OC rejoining with the Seven Deadly Sins if they are one, or coming across them if they aren't, along with Taro meeting with the Sins per the request of Merlin 

Scenario 3: After the defeat of Hendrickson, everyone has time to take it easy and relax during one of the festivals, and so we RP how your OC celebrates it

Scenario 4: Make your own, just explain to me what it is. 

You can request scenarios, and they will be made into future chapters.