In Mushoku Tensei as Servant Mordred Pendragon Alter (fanfic x Fate)

After winning a Holy Grail War as a Magus, Isaac transmigrates to Mushoku Tensei (Jobless Reincarnation) with the powers of his previous Servant Mordred Pendragon as a result of his wish to the Holy Grail.
...
Summary.
The Main Character Isaac is a male. He has a 16-year-old, handsome appearance similar to Mordred from the Fate series due to the effect of a Saber Class Card. Overpowered Protagonist.

The story starts in the Demon Continent, where the MC meets Ruijerd, 10-year-old Rudeus and the 12-year-old Eris.

The MC has a knowledge about Mushoku Tensei of up to 2nd Season of the anime.

I was recently inspired to give attempt in writing this kind of story, perhaps as a continuation of my other Mushoku Tensei story with the Reincaranted Protagonist Seraphim, but here with more action and fast-paced development in the original Mushoku Tensei World. I'm just giving it a try for now. Eventually, the MC could develop the same magical abilities as Seraphim in addition to his current toolkit.

The MC starts with buffed up statistics and abilities of a top-tier Saber Class Servant. It's a Strong to Stronger story. The Protagonist is an overpowered swordsman with a high talent for magic (previously undeveloped).

Because of his Dragon Aspect, the MC has a cheat-like affinity and talent for magic, being able to intuitively create magic techniques and sword techniques that others in that world could not.

Following through with his goal of becoming a supreme God-like existence and realizing his desires, Isaac sets off on a journey to make use of his travel to the new world to
elevate his magical abilities and strength to the next level.

...

Love interests: Guaranteed to end up with a harem of sorts.
I'm not entirely sure if Isaac will steal Eris and cuck Rudeus, but it's likely to happen.
Apart from that, very likely love interests are: Nina Farion (daughter of the Sword God), Roxy, Linia Dedoldia, Ariel Anemoi Asura and Aisha Greyrat.
Isaac is likely to bump into Elinalise during the journey, so it's possible they might end up together as well, depending on circumstances.
Other possible love interests: Nanahoshi, Ghislaine, Tristina Purplehorse and Isolte Cluel.

This ended up being a damn long list...

Anyway.
PS: The final title/cover wasn't decided on yet.

PS2: I feel that if the MC went in blind in that world his choices and the plot would be too forced (as it usually is in fanfictions with MCs that have no prior knowledge yet still end up following the same plot) so as a geek the MC has at least some basic knowledge of the Mushoku Tensei anime to make slightly educated choices based on that, like most readers would do.