A deer in a dream often represents gentleness paired with heightened alertness -- open and unguarded, yet ready to startle at any moment. Encountering a calm deer can reflect a tender part of yourself you're learning to trust in the open, while a deer that flees may point to vulnerability you're not yet ready to expose. The dream usually invites more patience with your own softer instincts.
Mars of a nativity, and not joined to good planets, signifieth the native to suffer by envy and hatred. - William Lilly (1602.-1681.)