Moody

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Old English mōdig ‘brave or wilful’ (see mood1, -y1).

wiktionary

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From Middle English mody, modi, from Old English mōdiġ(“brave”), from Proto-Germanic *mōdagaz(“courageous”); synchronically mood +‎ -y.

etymonline

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moody (adj.)

"angry, quarrelsome," 12c., from Old English modig "brave, proud, high-spirited, impetuous, arrogant," from Proto-Germanic *modago- (source also of Old Saxon modag, Dutch moedig, German mutig, Old Norse moðugr); see mood (n.1) + -y (2). Meaning "subject to or indulging in gloomy spells, out of humor, sullen" is recorded by 1590s (via the Middle English sense of "angry"). Related: Moodily.