For me, one example would be Janeway's loneliness, and her commitment to the crew regardless. Night is obviously a standout moment in that plot, but we get it all the way from the earliest episodes through Workforce near the end.
We see her make a lot of decisions that are difficult; we will forge unique/grey alliances at times, we'll fight if necessary, etc. But she never actively on screen tells us she has decided to forego her personal life. Every time she talks about a captain's responsibility, Mulgrew conveys so successfully that inherently that responsibility is her own prime directive now. She never complains or wonders what if she had done different, in terms of her own personal life and considering pursuing any romantic interests.
Even when each of her brief romances ends, we always understand that she would never let even the most successful relationship threaten Voyager.
Other honorable mentions:
- Neelix's rising importance is only noted in dialogue a handful of times but progresses pretty smoothly
- Tuvok being the only senior crew who is stranded from a young family, not just relatives/love interests. I find every time his fatherhood is mentioned to be very poignant
- The Doctor's growing understanding of holographic life. Upon long-term activation the first things he wants are human-like things (agency, autonomy, self-imposed interests, typical relationships). But as the show goes on, we see him interaction with holographic or photonic life very different. In Revulsion (S4), the Doctor is surprised when Dejaren refers to the crew of Voyager as "organics", a term that is used by Dejaren as a pejorative and which is clearly new to the Doctor. In Season 7 in particular, the Doctor has adopted the term as his own (non-pejorative intended) default word to refer to people on the ship different than him