dative に for attitude target

The particle に marking the target/recipient of an attitude or disposition expressed by an adjective: 私に親切だ ('kind to me'), 子供に厳しい ('strict with children'), 動物に優しい ('gentle with animals'), 自分の子どもに甘い ('soft on one's child'). The に-marked noun is the recipient of the trait expressed by the predicate adjective.