12 Minutes’ focus may be on its suspenseful time loop, but there is a bit of exploration and item gathering going on here too. In fact, it reminds us quite a bit of a point-and-click adventure game with you picking up things to put them in your inventory then combining them with other items. You will need to do this for the Fluidity achievement, which requires you to water the plant at least one time. Here is how to get the Fluidity achievement in 12 Minutes.
To get the Fluidity achievement in 12 Minutes, begin a new loop and immediately put your cursor on the mug on the kitchen counter to the right. When you pick it up, open your inventory and combine that with the sink to fill it up.
With the mug filled with water now, walk into the bedroom and combine it with the flower sitting on top of the dresser. You will dump the water into the plant and immediately earn the Fluidity achievement. Be careful about your cursor placement; if you are a little off, you will just set the mug down onto the dresser without watering it. No big worry though, you can just pick it up again and try a second time.