someone whose personality has two different parts, one very nice and the other very unpleasant.

You can't depend on him to be friendly - he's a Jekyll and Hyde.

• hail from
• hail from somewhere
• hair of the dog
• hair of the dog that bit you
• hair out of place
• hair-raising
• hair's breadth
• hair shirt
• hair-splitting
• halcyon days
• hale and hearty
• half
• half a dozen
• half a loaf
• Half a loaf is better than none.
• half-arsed
• half-baked
• half-hearted
• half-heartedly
• half the battle
• halfway house
• half-wit
• half-witted
• ham-fisted
• ham it up