Learn Hardcore French: Paul est malin, mais il reste honnête.

Malin: clever in a practical, shrewd, sometimes sly way; can suggest trickiness or street smarts. Depending on tone/context, it can be admiring or slightly disapproving.
Intelligent: cognitively smart, neutral/positive, no implication of slyness. Examples: Il est malin (He’s wily/savvy). Il est intelligent (He’s intelligent).

How do I say it if the person is female or plural? Is there anything irregular?

Malin has an irregular feminine: masculine malin, feminine maligne; plurals: malins, malignes.
Honnête is the same in masculine and feminine; add an s for plural: honnêtes. Examples:
Pauline est maligne, mais elle reste honnête.
Paul et Marie sont malins, mais ils restent honnêtes. Note: maligne is pronounced with a “ny” sound: [ma.liɲ].

How do you pronounce the whole sentence naturally? Any liaisons?

IPA (careful speech): [pɔl ɛ ma.lɛ̃ | mɛ il ʁɛst‿ɔnɛt]

Paul [pɔl]
est [ɛ]
malin [ma.lɛ̃] (final -n nasalizes the vowel; don’t pronounce a full “n”)
mais [mɛ]
il [il]
reste [ʁɛst]
honnête [ɔnɛt] Liaisons:
Recommended: reste honnête → [ʁɛst‿ɔnɛt] (link the -t).
Usually no liaison after mais: say [mɛ il], not [mɛ.z‿il].

Is the h in honnête silent? What does the circumflex do?

The h is a “mute h” (h muet), so liaison and elision are allowed: il reste honnête → [ʁɛst‿ɔnɛt].
The circumflex in ê signals an open “eh” sound [ɛ] and often traces a lost historical s (Latin/Old French honeste → honnête).

Does rester mean “to rest” here?

No. Rester here means “to remain, to stay (in a state).” With adjectives, it means the quality continues: il reste honnête = “he remains honest.”

“To rest” is se reposer.
Near-synonyms for this use: demeurer (more formal), continuer d’être.

Why use il reste honnête instead of il est honnête?

Il est honnête states a fact.
Il reste honnête emphasizes continuity or contrast: despite other factors (e.g., being malin), he still remains honest. It matches the contrast introduced by mais.

How do I say it in the past or future?

Past (passé composé): Il est resté honnête. (Auxiliary: être; agree the participle: resté/restée/restés/restées.)
Imperfect: Il restait honnête.
Future: Il restera honnête.

Is the comma before mais necessary in French?

It’s standard to put a comma before mais because it marks a contrast and a pause. In very short clauses, some writers omit it, but most style guides recommend it: …, mais ….

Could I drop il reste and just say Paul est malin mais honnête?

Yes, that’s natural and means “Paul is clever but honest.” However, removing reste loses the “still/continues to be” nuance; reste strengthens the contrast.

Is malin informal? What are good synonyms?

Malin is common and neutral in everyday French. Depending on nuance:

Positive/neutral clever: astucieux, futé, débrouillard.
Sly/cunning: rusé.
Pure intellect: intelligent. Set phrases: un petit malin (a sly/clever one), exclamatory T’es malin ! (often ironic: “real smart move!”).

Can malin mean something like “malignant” or “devilish”?

Yes, in other contexts:

Medicine: un cancer malin = malignant cancer.
Religious/literary: le Malin (capital M) = the Devil. In your sentence, context clearly means “clever/shrewd.”

Why is it il after mais, not lui?

Il is a subject pronoun and must be used as the subject of reste. Lui is a disjunct/stressed pronoun used after prepositions or for emphasis: Mais lui, il reste honnête (emphatic: “But he, he remains honest”).

Is there liaison after est in Paul est malin?

No, because malin starts with a consonant (m). You would make a liaison if the next word started with a vowel or mute h: Paul est honnête → [pɔl ɛ t‿ɔnɛt].

Could I replace mais with something else like pourtant or bien que?

Adversative adverb: Paul est malin ; pourtant, il reste honnête.
Concession with subjunctive: Bien que Paul soit malin, il reste honnête.
Other options: cependant, néanmoins, alors que (with different structure/nuance).

What’s the difference between rester and demeurer here?

Both can mean “to remain” with adjectives:

Rester is the default, neutral choice.
Demeurer is more formal/literary in this sense and also means “to live/reside” in other contexts. So: … mais il demeure honnête is correct but a bit more formal in tone.