Rotation being forced away from what I want

So I have a script for character movement. I have a script that forces the character to face the direction of movement. Problem is for my character, I need the rotation to be X: 90, Y, 180.

Here is my script. It works fine for what I want to do above, but it forces the X and Y rotation to 0. How do I fix this?

	private GameObject parent;
	private Vector3 dir;
	void Start(){
		parent = transform.parent.gameObject; //The object uses its parent's velocity
	void Update () {
		Vector2 dir = transform.parent.rigidbody2D.velocity;
		float angle = Mathf.Atan2(-dir.y, -dir.x) * Mathf.Rad2Deg; 
		transform.rotation = Quaternion.AngleAxis(angle, Vector3.forward);

Option 1 (easy option): set your object to the child of something else, and then rotate the parent around the z direction.

Option 2: Save your desired rotation in a variable and apply your rotation around z as an additional rotation.

Quaternion initialRot;

void Start(){
    initialRot = this.transform.rotation; //or possibly Quaternion.Euler(blah blah)

void Update(){
    transform.rotation = initialRot*Quaternion.AngleAxis...;

It is possible that for this, you may need to convert Vector3.forward into local space before rotating around it, see Transform.InverseTransformDirection.