Generally hangout on this discord, The Distorted Shadow writes some interesting fics as well.
Challenges: PM if you accept them so I can read and discuss the ideas with you and read the story.
A Devil Survivor x Rosario Vampire Crossover
This can be a post 'Song of Hope' (Gin/Haru route) Kazuya taking Tsukune's place in the Rosario Vampire plot. This can be easily done as Mikogami, the schools principal, decides to bring Kazuya instead, as he sees him as someone who can both help relations between Humans and monster and as someone who is more than strong enough to easily survive Yokai academy.
Kazuya of course keeps all the skills which he learnt during his time in Devil Survivor, which is already shown after all the demons were back sent to the demon world and he has to fight and banish Babel.
Kazuya would also have much different interactions with the Rosario cast, as he's a much different character to Tsukune. One of the Rosario cast could also possibly recognise Kazuya from their own time of being trapped in the lockdown.
During his time at the academy, Kazuya is slowly learning to use the power of the Bels which he had previously absorbed. Kazuya himself can also be classified as a 'Bel' race, as even though he hasn't absorbed Babel he has become the King of Bel, and will stop aging sometime during his early to mid twenties. He can also speak to the Bels that are currently inside him, at least those who want to speak to him.
Some of the Bels would be more accepting in helping him learn their powers, such as Belial and Beelzebub, compared to others, such as Beldr and Belberith. He also can't learn Beldr's special ability of immunity to everything but mistletoe.
Apart from having to deal with the situations of Rosario Vampire, involvement of Devil Survivor elements will effect him during his time in Yokai Academy. This involves Loki somehow becoming a teacher of history for the academy while also trolling Kazuya, Naoya still trying to make Kazuya stronger by putting him in situations where he can get stronger, Nebiros and Alice deciding Kazuya must work with them now, maybe having Kazuya interact with Okuninushi, the Japanese creator god in the game and involving some NG events, which Kazuya did not experience.
Tomb Raider remake and Campione crossover
In the Tomb Raider remake from 2013 Lara Croft managed to defeat Himiko at the end of the game. For this crossover Himiko could be considered the Heretic God Himiko, and Lara became a Campione through this, along with gaining one or two authorities of your choice that are based off Himiko or her legend.
For the timeline of the fic, setting it up after the main Campione storyline would be most interesting.
As an archaeologist Lara would continue to looks for historical sites. However, with the help of the magical community, Lara would now have access to knowledge and information towards sites that would be unavailable to the mundane population. What you choose to do with this is up to you.
Crash bandicoot and Familiar of Zero
Virtually, Louise summons either Crash or Coco bandicoot.
This fic idea can be considered semi-crack.
Fate Series and Highschool DxD
I had this idea since reading Drow79's fic "Holding all the Card".
After Kiba/Isaiah managed to escape the facility where the experimentation for the Holy Sword project was being carried out he was rescued by either Zelretch. Zelretch decides, to see what happens, grant Kiba power by giving him servant cards with the souls of certain servants...after complaining that he want's to see someone else be the main character to help the world instead of Shirou or Issei, which confuses Isaiah.
The servants (most are negotiable) are:
Saber- Gawain (Non-negotiable)
Berserker- Sakata Kintoki
Ruler- Saint Martha (Non-Negotiable) The Fate/Apocrypha has proved she is a ruler class servant in her normal form.
Avenger- Hessian Lobo
For servant selections, I would prefer to see each servant originating from a different background, although this isn't compulsory. By this I mean one servant is of Arthurian origin (Gawain), one Christian (Saint Martha), one Greek, Japanese, Jewish, British, etc. It would be interesting to see the eventual reactions of the different servants by different factions, like the Pendragon family to Gawain and the Church and heaven to Saint Martha.
Zelretch gives Isaiah a name change to Kiba and gives him to a family (your choice OC or not) to raise who know about the supernatural world at Kuoh. He also gives instructions to Kiba to start training his power through the sacred gear and what he gains from equipping his servant cards. He will also send Kiba on soma adventures around Japan against enemies Zelretch thinks are around his level at the time he sends Kiba. Because of this Kiba will have a bit of a reputation by the time the Highschool DxD canon should start and his actions might have already changed how the story of DxD will play out, with more divergences as the story progresses.
Gawain and Saint Martha will be the first servants Kiba will have available, both wanting to help Kiba after what had happened to him with the Holy sword project. By the time Highschool DxD canon should start Kiba should have at least 4 servants available for him. He will need to reach a better understanding with each servant however to unlock their power and use it better.
The Distorted Shadow's Ideas.
These are Fic ideas from The Distorted Shadow that he doesn't have the time to write or lost interest. PM me if your interested and maybe create a thread in TDS' forum's to discuss the fic.
Harry Potter and Fate/Stay Night idea:
The Grail of the Second Wizarding War
Okay... basic summary:
Salazar Slytherin and Rowena Ravenclaw researched the Throne Of Heroes and ended up with the foundations for a Holy Grail System ala. TYPE-MOON's Fate franchise but never finished it. Tom Marvolo Riddle found the research when he was in Hogwarts due to it being kept in the Chamber Of Secrets. Tom spent decades adjusting the research and eventually managed to create a fully functioning Grail System before going and getting himself blown up against Harry. After his resurrection, Tom is eventually reminded of the system when a set of command seals blossoms on his hand, indicating that the Grail is now fully charged and ready for actual use. Harry, due to his connection to Tom discovers this and copies the ritual, grabbing Hermione and Ron to help since the adults would probably waste too much time arguing about it. Eventually the trio summon a set of servants while the other 4 are summoned by death eaters.
The List of servants:
Harry Potter- Ruler - Jeanne d'Arc
Ronald Weasley - Saber - Fergus mac Róich
Hermione Granger- Caster - Helena Blavatsky
Tom Riddle - Assassin - Hassan Of The Cursed Arm
Lucius Malfoy - Archer - Gilgamesh
Bellatrix Lestrange - Lancer - Elizabeth Bathory
Augustus Rookwood - Rider - Ozymandias
You can change the servants to who you feel fits best and the Death Eater masters if you want but Tom and the Hogwarts must be masters.