Dan Michel's Ayenbite of Inwit (fl 1340), a (Kentish) Middle English translation of a French treatise, shows interesting idiosyncratic features in the areas of orthography and lexis (cf. Scahill, “Dan Michel: Fossil or innovator?”, John Benjamins, 2002, for example). From a syntactic perspective, a preliminary overview of the text reveals that Dan Michel has a strong preference for the verb of necessity bihoven (>PDE behove , see MED s.v. bihoven ), itself a relatively marginal verb in the period, rather than for higher frequency verbs such as thurven (< OE þurfan , see Bosworth & Toller), dominant in Old English, and neden (>PDE need ), incipiently gaining ground in Middle English (see Loureiro-Porto, The semantic predecessors of need in the history of English (c750-1710), Blackwell, 2009 for a recent corpus-based study of this). Such a preference for behove , however, is not found in any other Kentish text considered in the present article, which suggests that it is not a dialectal feature. The use of behove as a verb of necessity in Ayenbite of Inwit will be studied in this paper, looking at whether in addition to its unusually high frequency it also behaves in an idiosyncratic way from a semantic-syntactic point of view. The ultimate aim will be to discover reasons behind the exceptionally frequent use of this particular verb of necessity at the expense of other such verbs available in the language. I will pay close attention to its syntactic function and semantic connotations, in an attempt to ascertain whether the translator's choice is to some degree determined by intralinguistic factors. This study will also compare Ayenbite of Inwit to an older version of the same text, The Book of Vices and Virtues ( c. 1450), in order to establish whether this specific text-type requires the occurrence of behove . The conclusions will show that neither the linguistic context nor the text-type play any role in the author's exclusive selection of behove . Rather, his preference for behove as a semantic-syntactic substitute of thurven and need is a characteristic of his own idiolect, which brings it close to other Germanic languages in which cognates of behove are the main necessity verbs (Dutch, for example). At the same time, the conclusions drawn suggest that the features of behove in Ayenbite of Inwit might be interpreted as indicative of an incipient grammaticalization of this verb.