Of course Mary would start being much kinder to Darnley after discovering he's sick despite everything he's done to her. It felt like a very Mary thing to do. When Lady Lennox claims that she is really trying to get him out of the way, though, it doesn't seem like that far-fetched of a fear for someone like her to have. It's what most people would probably try to do.
Lady Lennox's continued push to get Darnley more power started to feel unbelievable around this episode though. I get that she wants power, but she knows that Darnley is hallucinating. After this episode, it seemed obvious that she saw his hallucinations as an asset because she could tell him to do what she wanted, but that's clearly not the case. In reality, it just made Darnley more unpredictable, and he was probably harder for her to control than he was before. Imagine if she'd let him get treatment and, once he was better, work on getting more power. Imagine how much better that might have worked out for the both of them.
Baby James is finally born, which I had been waiting for. It was exciting largely because of his place in history. The show had been so focused on Elizabeth and Mary both vying for England (though that was remarkably a smaller focus throughout season four), which made James' birth towards the end of the show felt fitting, though I'm still not sure how I feel about all of the timeline twisting to make it happen. (This season really cemented for me that Reign was meant to end at Francis' death and just be the story of their marriage, not Mary's life afterward.)
The possibility that Jane was working for Narcisse never occurred to me, and it felt as if it were almost out of nowhere. Working for Narcisse is honestly the worst idea.
I'm not as confident as some of the characters on the show that Henry would be a better king than Charles. For all the rash decisions that Charles makes, Henry never proved himself to be any better. Any advantages he had seemed to be entirely based on the idea that he looked "healthier", which leaves me frustrated that anyone would make him king for that reason alone. Honestly, I'd forgotten why Spain wanted him as king over Charles by this episode. Was there even a reason beyond the looks thing?
For a little bit, I was hoping Leith would come back, but nope, we learned that he was getting married after a courtship that happened entirely off screen. I know I said that I wanted to know that Leith was happy, but I don't think this did that for me. We never saw the girl or heard how Leith feels. For all we know, she could be purely a rebound. If anything, I would have preferred to never hear about Leith again than get the small mention that we did. I'm incredibly frustrated with how the end of his story was handled. Actually, I think it would have been best if he had actually died and hadn't come back in season four.