Hi! Thank you for taking interest in my rarepair 😭
Sorry I haven't been able to formula their love story in proper manner...
But I will try list down the step before they gotten together:
1. The first meeting which is during the academy years, where Sentinel got hurt and Ratchet treating him. He scolded the young bot alot but what I can say that the young one always don't listen :3c
2. Then came the canon timeline where they meet in S2 to wash and disinfect the "earthly organic germs". They don't remember each other from the early years.... (I know during S1 they have a comm link talk but Sentinel was mainly focus on Optimus and didn't see Ratchet)
3. So, something bad and angst happened to Sentinel, and Ratchet was the first to notice something is amiss as a medic and sorta "saved" him. This is when Sentinel starting to take notice of the rust bucket he once called.
4. Sentinel done alot of stupid dumb things to gain Ratchet's attention (testing boundary I guess). It's effective since Ratchet starting to get annoyed and noticing Sentinel.
5. Of course we hate Sentinel, so something more seriously bad happen to Sentinel, Sentinel almost got so depressed and unwarranted thoughts occur. He refused any help from others and shut himself out. (most people will feel frustrated with him and don't want to bother him anymore). Ratchet being a responsible medic he is, couldn't let Sentinel being alone and helpfully accompany / hug him. Slowly nursing Sentinel back to his usual obnoxious self (unfortunately).
6. Sentinel being clingy and only open up more for Ratchet. Ratchet sorta soften up to Sentinel after discovering Sentinel's vulnerable side and understand why he is being so difficult to everyone in the past.
7. And voila they finally try dating together!
Thank you for the ask!