I also like 'The Lost Years'. It fills in the gaps of the characters' lives that were not fully explored in the show. It's full of interesting backstories and character development.
One possible comfort scenario could be after a particularly difficult mission. Five, with his time - traveling experience, might share some wisdom with Vanya to soothe her. For example, he could tell her that the chaos they face is all part of a bigger plan and that she has an important role to play in the grand scheme of things. This would give Vanya a sense of purpose and comfort.
One great 'Umbrella Academy Luther x Fanfiction' is 'Luther's Redemption'. It focuses on Luther's journey of self - discovery while also exploring his relationship in a very heartwarming way. The author does a great job of staying true to Luther's character as we know it from the show.
There could be a fanfiction where Five and Vanya accidentally swap powers. Five suddenly finds himself with the power of soundwaves while Vanya can time - travel. This leads to a lot of chaos as they both struggle to control their new abilities and also have to deal with the implications it has on their relationships with the other Umbrella Academy members.
One theme could be acceptance. Five could accept Vanya fully, powers and all, which would be a great comfort to her. He might tell her that her powers don't make her a monster but rather a unique and important part of the family.
You can start by looking on fanfiction websites like Archive of Our Own (AO3). Just search for 'umbrella academy five and vanya' in the search bar, and you'll get a list of relevant fanfictions. Sort them by popularity or rating to find the ones that are well - liked by other fans.
A new character could be introduced as the antagonist. This character could be a time - traveling bounty hunter who has been sent to capture Five while he is sick. The bounty hunter might believe that Five's sickness makes him a danger to the time - space continuum and wants to lock him away in some sort of time - prison.
Another plot could involve Five getting sick due to some side - effect of his powers overusing them in a short period. As he gets sicker, he starts to lose his memories of different timelines he has visited. The story could then focus on his journey to regain those memories with the help of his siblings.
It's appealing because it gives fans the chance to fill in the gaps. The show might not cover every aspect of Luther's relationships in detail. Fanfiction, especially the Luther x ones, can take those loose ends and create entire storylines around them. For example, exploring how Luther would handle a romantic relationship given his upbringing and the events he's been through in the series.
Some fanfictions might have a plotline where Five is hurt because of his own reckless behavior. He's a complex character who sometimes dives headfirst into dangerous situations without fully thinking things through. So, he could end up hurt as a result of his own impulsiveness. Also, there could be a plotline where Five is hurt emotionally by his family's lack of understanding or acceptance of him, which then leads to some sort of physical or mental breakdown.