Diablo’s Loyalty to Rimuru Explained
When you watch That Time I Got Reincarnated as a Slime, Diablo stands out immediately.
Elegant, charismatic, terrifying, and completely loyal to Rimuru — almost to a frightening degree.
But Diablo’s loyalty isn’t blind.
It isn’t worship.
It isn’t even admiration in the traditional sense.
His devotion to Rimuru is rooted in identity, purpose, and recognition — things Diablo had never experienced before meeting him.
This is not a simple master–servant dynamic.
It’s one of the most philosophically layered relationships in the entire series.
Diablo does not serve Rimuru because Rimuru is strong — he serves Rimuru because Rimuru is meaningful.
1. Before Rimuru, Diablo Had Power but No Purpose
Before Rimuru summoned him, Diablo (then known as Noir) was already one of the most powerful Primordial Demons.
Ageless
Formless
Limitless
And bored.
He had strength every other being feared — but nothing to direct that strength toward.
His only source of stimulation was watching humans:
https://tensura.fandom.com/wiki/Diablo
Not admiring them.
Observing them.
He was fascinated by:
Their struggle
Their emotional chaos
Their desperation to find meaning
Because he did not have meaning himself.
Power without purpose is emptiness.
Rimuru changed that.
2. The Moment of Recognition: Rimuru Saw Diablo as a Person
When Rimuru summoned him, Diablo didn’t just recognize Rimuru’s power.
He recognized Rimuru’s belief in coexistence — not dominance.
Rimuru treated him:
Not as a weapon
Not as a monster
But as an individual
That is something even demons are not used to.
Rimuru gave Diablo a name, and naming in Tensura is not symbolic — it is spiritual acknowledgment.
Naming = acceptance → identity → existence made real.
For a being as ancient and detached as Diablo, this was world-shattering.
Diablo isn’t loyal because Rimuru commands him.
He’s loyal because Rimuru saw him when nothing else ever did.
3. Their Values Align Perfectly — And That Matters
Rimuru’s worldview:
Build a place where everyone belongs
Protect those who trust you
Carry responsibility willingly
Diablo’s worldview:
Devotion requires intention
Power means nothing without direction
Loyalty is sacred
Their philosophies match — not mirror.
Rimuru creates meaning.
Diablo needs meaning.
This is not subservience — it is compatibility.
4. Diablo’s Loyalty Is Not Based on Strength
Many fans assume Diablo serves Rimuru because Rimuru is powerful.
But Diablo has followed Rimuru even before Rimuru became a Demon Lord.
That proves something important:
Diablo is loyal to Rimuru’s potential, not his current strength.
Diablo saw something in him before anyone else did.
This is confirmed in the light novels:
“I knew from the beginning. You are destined for greatness.”
(LN Volume 6)
He serves who Rimuru will become, not just who he is.
5. Rimuru Gives Diablo Freedom, Not Restraint
Most powerful beings in isekai command their followers through fear or hierarchy.
Rimuru does the opposite.
He lets Diablo:
Act freely
Judge freely
Fight freely
Rimuru trusts Diablo.
That level of trust is rare and Diablo treasures it more than life.
This is why he smiles during battles —
He is expressing joy in being allowed to act as he is.
Loyalty isn’t obedience.
Loyalty is choosing someone every single day.
6. Diablo’s Devotion Is the Purest Form of “Found Purpose”
Rimuru didn’t just change Diablo’s life.
He gave him a reason to live with intention.
For Diablo:
Rimuru is not a leader.
Rimuru is not a master.
Rimuru is a purpose.
It’s not worship.
It’s not obsession.
It’s clarity.
And that’s why his loyalty is unwavering —
It’s who he is now.
Conclusion
Diablo is not loyal because:
Rimuru is strong
Rimuru commands respect
Rimuru gave him a name
Those things matter — but they’re not the core.
Diablo is loyal because Rimuru gave him meaning.
And for a being who has lived longer than entire civilizations —
meaning is the one thing he never had.