Definitely Ben and Liara. Liara has strong biotic abilities and knowledge of the Protheans. Ben could bring his alien forms' powers to the table. They could combine their powers to uncover ancient secrets in the Mass Effect universe that might be related to Ben's Omnitrix or his alien origins.
I think a pairing between Ben and Tali would be really cool. Tali is a brilliant engineer, and Ben's Omnitrix is a high - tech device. She could help him understand and maybe even upgrade it, while he could protect her with his alien powers during their adventures.
Well, it could be about Ben using his alien forms to fight alongside the Mass Effect characters against a common enemy like the Reapers. Maybe his Four Arms form could be used for brute strength in hand - to - hand combat with the husks.
A great Mass Effect crossover fanfiction idea could be a crossover with the Stargate universe. The Mass Effect races could discover the Stargate network and start exploring other galaxies through it. There could be conflicts and alliances with the various races in the Stargate universe. Also, a crossover with the Dragon Age series might be interesting. The mages and warriors of Dragon Age could interact with the biotics and soldiers of Mass Effect. They could learn from each other's magic and technology, and perhaps even fight together against a dark force that threatens both universes.
Shepard and Master Chief could be an interesting pairing. Shepard is a very diplomatic and charismatic leader in the Mass Effect universe, while Master Chief is a stoic and highly skilled soldier in the UNSC. Their different leadership styles could either clash or complement each other. They could learn from each other's combat and decision - making skills.
Sakura and Liara would make an interesting pair. Sakura, with her medical ninjutsu skills, could collaborate with Liara, who is also very knowledgeable in the medical and scientific fields. They could exchange knowledge about different forms of healing and perhaps even come up with new techniques by combining their respective medical expertise.
Alex Mercer would be the most interesting. His abilities are so unique. In the Mass Effect universe, he could completely disrupt the power balance. He can shapeshift into anyone, which means he could infiltrate the Citadel Council or any other important organization with ease. His superhuman strength and regenerative abilities would also make him a formidable force against the enemies in Mass Effect, like the Collectors or the Reapers.
One interesting concept could be the crossover of different species from the Mass Effect universe in unexpected ways. For example, seeing Asari and Krogan working together in a completely new scenario that was not in the original games. Another could be the melding of Andromeda's technology with that of the Milky Way's in unique and creative ways, like a new type of weapon or ship design.
One idea could be the Pilots from Titanfall teaming up with the Normandy crew in Mass Effect. They could share their combat skills and technology. For example, the Pilots' parkour abilities might amaze the Mass Effect characters, and in return, the advanced biotics and tech of the Mass Effect universe could be useful for the Titanfall side.
One interesting concept could be the combination of the advanced technology from Crysis with the diverse alien species in Mass Effect. For example, the Nanosuit's capabilities like enhanced strength, speed, and cloaking could be integrated into a Mass Effect - style story. Maybe a human character wearing a Nanosuit gets involved in a diplomatic mission among the various alien races in the Mass Effect universe, creating unique situations where they have to use the suit's features to survive and influence the outcome.
The idea of chakra being used in the Mass Effect universe is also very cool. Since the Mass Effect world has its own forms of energy, seeing how chakra could interact with biotics or other forms of technology would be exciting. It could open up new ways of powering devices or enhancing biotic abilities.
In Doom Mass Effect crossover fanfiction, the technology aspect is fascinating. The advanced tech in Mass Effect like biotics and omni - tools could be juxtaposed with Doom's hell - inspired weaponry. Maybe a story where Shepard gets access to some of Doom's weapons and has to adapt to their raw power.