Usually, the use of paralleling is to create an effect of nostalgia, to remind viewers of the old days when all these characters you have fallen in love with were younger, new to the show and have yet to make the mistakes and decisions that will make viewers cry. One of my favourite ways this has been done is in Suits. The show was cancelled after its eighth season finale. However, much like what happened with Sense8, the fandom was livid, got the hashtags trending on Twitter and it was picked up for a final 'goodbye' season.
It's a trope that essentially makes you reminisce on the earlier seasons
As a result, the producers decided it was a good idea to fill the season with little nuggets, little references to the earlier seasons that broke mine and many others hearts in the process. For example, we got a verbal reference to when Mike's suitcase full of weed opened up in his interview, a scene that kicked off the show back in its first season and began his career in the lawyer business. The show also blessed us with a beautiful montage of clips from earlier seasons. It's a trope that essentially makes you reminisce on the earlier seasons and reflect on how far these characters have come and how much HAPPIER they are now as we realise there will never be another episode to watch, another moment between these people we've rooted for and fallen in love with.
Suits is not the only show that has followed this trope, as after just finishing binging 12 seasons of Bones, the parallels in the final episode had me very emotional. There were references to when Brennan and Booth sang 'Hot Blooded' by Foreigner, referencing to when they first kissed, to many other moments that made these characters a family who will go to the end of the world to protect each other. What I especially like about the finale of Bones is that the final scene ends with Brennan and Booth walking away in the distance, the same way they walked away at the end of their first episode. It's nostalgic, maybe even bittersweet as you realise this is the end. Again, similarly to Suits, the finale reminded me how far these characters have come and what they've had to endure and battle to be where they are now. It also reminded me of how incredibly different they looked at the beginning (some of the hairstyles are truly atrocious and I'm so very glad that Brennan grew out of her chunky ugly necklaces!)
It makes it feel that little bit more special and memorable
If, like me, you're a Tumblr addict and after binging a show, you're there on the tags, living off the GIFs and the art that talented people out there produce for nerds like us, you can most definitely find gifsets of these parallels I am waffling about on. I'm sure there are also many other shows that use the same trope other than these two.
Ultimately, parallels allow a show to produce a nostalgic finale or final season that enables viewers like myself who get a little TOO invested to bask in the final moments and remember the memories of previous seasons. For me, it adds a much more final tone to the end and makes it feel that little bit more special and memorable.