Interception!

I was thinking about how to do interception in D&D. Like, playing the bodyguard and taking an arrow or sword for someone. I have been thinking about how I want to do it. I've come up with some ideas.

The Approach

First off, I think I know what I want from it.

1. I'd want the bodyguard to act out of initiative, but then use up their turn. I think that's fair, given that they are taking what could be a death dealing blow. That's a pretty big risk.
2. In addition, I'd also want them to have to make the decision before the attack roll is made. I like keeping that uncertainty when doing this potentially powerful maneuver.
3. I'd also be okay with them moving into position, as long as they could make it with a full round of movement and wasn't already engaged in melee combat. They could disengage, but they'll be attacked 
4. But, the key is that when they end their movement, they have to be adjacent to the target (if taking a melee hit), or between the shooter and the target (if taking a ranged hit).

What I haven't figured out is which of these methods are going to be the way I want to do interception. Let me list them.

Interception #1

The player can elect to intercept a hit against a target. As long as they haven't acted this round, the bodyguard can make a full movement and take the hit automatically if it would hit the target. The interceptor takes the damage as normal and ends their turn.

With this method, the bodyguard would automatically protect the target once per round, as long as they can reach them. There's the initiative limit on how often they can do it as well as the HP limit. It is simpler than method #2, but it does mean that the person gets automatically hit, despite their armor.

Interception #2

The player can elect to intercept a hit against a target. As long as they haven't acted this round, the bodyguard can make a full movement and attempt to take the hit. If the enemy's attack roll is higher than the target's AC but lower than the bodyguard's AC, then the bodyguard takes the hit but no damage. If the enemy's attack is equal or higher than the bodyguard's AC, then they take the hit and receive damage. Either way, the bodyguard ends their turn.

This way is a little more complicated, but rewards a bodyguard that has a lot of armor. It does lower the risk a bit for a plate mail wearing guy, but at the same time, it does reward a bodyguard for wearing good armor. And I feel armor should play a bigger part in this.

I'm learning towards #2 as I do want armor to play a part in this. I'd actually prefer that armor was a damage reduction rather than part of AC for this, but I'm not sure how I'd do that one for ACKs. So what do people thing?