A plot could involve Prince Blueblood getting into some trouble due to his prideful nature. Twilight Sparkle then tries to teach him a lesson about humility. For example, he could accidentally offend an important diplomat and Twilight has to help him make amends while also making him see his own flaws.
One idea could be that Prince Blueblood has to team up with Twilight Sparkle to solve a mystery in Canterlot. Maybe a series of magical artifacts are disappearing and their combined knowledge and skills are needed to figure out who is behind it.
Perhaps there is a magical competition in Equestria. Prince Blueblood initially underestimates Twilight Sparkle. However, as the competition progresses, he realizes her true strength and they end up forming an unlikely friendship as they compete against other powerful ponies.
Their relationship might develop as they study magic together. Twilight Sparkle is a very studious pony when it comes to magic, and Prince Blueblood, though not as dedicated, has some knowledge. As they exchange ideas and spells, they gradually become friends. For instance, they could discover an ancient magic text that requires both of their magical abilities to unlock its secrets, and during this process, they learn to respect and care for each other.
One interesting plot could be that Twilight's dragon transformation is part of a test by a powerful magical being. In her dragon form, she has to complete a series of challenges in a dangerous dragon - inhabited land. The challenges could be related to controlling her new form, using her dragon - specific powers, and also learning about the history of dragons. This would not only test her physically but also her mental and emotional strength.
One plot idea could be Twilight Sparkle getting cold feet before the wedding and her friends having to reassure her. Another could be a magical mishap during the ceremony that causes chaos but in the end makes the wedding even more special. Maybe an old enemy tries to disrupt the wedding but Twilight's love for her partner overcomes all obstacles.
Well, a great plot could be Twilight Sparkle as an Alicorn going on a journey to discover the origin of Alicorn magic. This could involve her meeting ancient Alicorn spirits and learning secrets about her own powers. Or perhaps she gets caught in a time - loop where she has to repeatedly use her Alicorn powers to break free and figure out what's causing it. It could also be interesting if she has to teach other ponies how to use Alicorn - related magic.
A plot could involve Flash Sentry and Twilight Sparkle teaming up to organize a magical event in Equestria. However, things go wrong when a jealous pony tries to sabotage their plans. They must then work together to overcome the obstacles, find the culprit, and still make the event a success. This would show their problem - solving skills and how their different personalities complement each other.
One plot idea could be them going on an adventure together to discover a new type of magic in Equestria. Another could be Timber helping Twilight with a difficult spell she's been trying to master.
A plot could involve a race between Thomas and one of Twilight's flying friends. Twilight has to referee and make sure it's a fair race. Along the way, they discover that there are some dark forces trying to disrupt the race, and they have to work together to stop them and ensure the race is completed successfully.
One idea could be that the twin brother has a different magical specialty. For example, while Twilight Sparkle is great at magic related to friendship and harmony, her brother could be more attuned to magic of the elements in a different way, like having the power to manipulate natural elements more directly. Maybe he could use his magic to help protect Ponyville from a new, different kind of threat that Twilight's magic isn't as effective against.
A plot idea could be that Twilight Sparkle's marriage is part of a prophecy. The whole ponyville would be in a festive mood preparing for the big day. There could be a series of events where Twilight has to fulfill certain tasks before the marriage as per the prophecy. For instance, she might need to find a special magical artifact. This would make for an exciting story as she goes on a quest with her friends. Another plot could be that Twilight marries a non - pony character, which causes a stir in Equestria. Some ponies might be skeptical, but Twilight stands by her love and they both prove that love knows no species boundaries. Also, a plot where Twilight's wedding is a double wedding with one of her friends could be really fun, with all the chaos and joys that come with two weddings happening simultaneously.
Maybe the fanfiction could explore a magical accident that results in a baby - like entity being created between Twilight and Flash Sentry. They then have to figure out how to take care of this new being while also trying to reverse the magic if it's not meant to be. For example, they might seek the help of Princess Celestia to understand what happened.