Protector

Adventuring is a dangerous work and some of your allies might not be as durable as you are. Fortunately the archetype of protector allows you to save your squishy wizard from certain doom by the hands of a goblin wielding a hair it plucked out of the other wizards beard. You can prevent your teammates death a number of ways including jumping in front of attacks, weakening enemies or making sure enemies never get close enough to hit anyone. 

Guardian

Beginning when you choose this archetype you can choose one person to focus on defending. When initiative is rolled, you can choose one friendly creature as the focus of your defence, you can switch to another friendly creature as a bonus action. You have advantage on attacking enemies within 15 feet of this creature. Additionally, if this creature is attacked you can use your reaction to move up to your movement speed towards them and then take an action, if you have a shield you can use this action to increase the creature’s armour class by the amount increased by the shield. you can do this a number of times equal to your proficiency bonus. 

bodyguard

Also at 3rd level, any friendly creatures within 5ft of you get a bonus to their armour class equal to half your proficiency bonus.

Interception

Starting at 7th level you can jump in front of an attack. If a friendly creature within 10 feet of you gets attacked (15 feet if they are the focus of your protection), you can use your reaction to try to jump in front of it. When you do so you must make a dexterity (acrobatics) check. If you succeed you impose disadvantage on the attack and it hits you instead, if you fail, the attack still has disadvantage but it hits the original target. Regardless of the outcome of the dex check you end up 5 feet away from the target but now in between the attacker and the target. If that space is occupied you can move the target 5 feet in the direction opposite the attacker. If that space is occupied you are unable to use this feature.

Inspiring protector

At 10th level when you use your second wind another creature you choose within 20 feet of you also regains the same amount of hit points.

Protective instincts

At 15th level you gain the following benefits:

• you can use your interception feature from an extra 10 feet away, if you do it from 5 feet away you automatically succeed the dex check.
• When you intercept an attack it deals half damage regardless of who it hits.
• the range of your guardian feature increases to 30 feet.
• allies within 10 feet of your now benefit from your bodyguard feature 

Unmoving sentry

At 18th level you become a veritable wall on the battlefield. If you forgo movement on your turn you count as three quarters cover until you move. While doing this you can make opportunity attacks against creatures that come within your attack range, and as a bonus action on your turn you can expend a use of your guardian feature to let an ally move up to their speed towards you (if they choose to) and take an action.