The Guard

The Praetorian, the Varangian, the Konoe Shidan,  and many more, all share one thing in common all not just guards, but the elite of the elite . The best of warriors tasks to be the guards for the most important people of their empire their nation, you are one of them, or at least you are in training to or aspire to be one, find  your charge keep them safe, stand not for yourself like every arrogant adventure but stand for something more, die for a cause you believe in.  

To your charge

You are the guard, the guard of someone who is important, important to you or to your people either you need the skills to keep them safe. One must not leave those they are ordered to protect in the face of danger for long, and quick reaction time is key to that. Beginning at level three you gain the ability to select your charge, (usually this might be something pre planned with another player, but you might want to make it more organic and something your character decides after getting to know someone), you may for now at least pick one and only one charge, once pick you are now the protector of that person and unlock ability, maneuvers to keep them safe. The first of these if To your charge, as a reaction if your charge takes damage you may move up to half your movement to them, you may use this as much your proficiency bonus. 

Push them back.

Your charge is your life you must face danger so they don't have to. The best way to protect your charge is to put your self between them and danger. As such beginning at level 3 you gain the ability of push them back, as a reaction if a creature should successfully hit your charge with a 5f reach melee hit you may as a reaction make an attack roll against them, on a hit you do damage as normal and push the creature back 5f while also moving 5f forwards as well to keep them in range, you can do this as many times your proficiency bonus.  

Push them back

Your charge is your life you must face danger so they don't have to. The best way to keep your charge safe is to put yourself between them and danger. As such beginning at level 3 you gain the ability of push them back. As a reaction when a creature successfully hits your charge with a 5f reach melee attack you may make an attack roll against them, on an hit you do normal damage as well as pushing them back 5f (if able) and you move 5f in their direction to follow them, you may do this as many times as your proficiency bonus.   

Their not heavy

In dire times you and your charge may not be able to stay and fight, sometimes you have to run and at the worst of times you may have to carry your charges unconscious body away to safety. To do this your highly trained body has got accustom to fast runs you gain an extra 10f of movement and you are so used to caring for your charge you don't lose half your movement when carrying them.   

Savage defender

In the largest and boldest battles, in the curliest of ambushes from all sides your charge may be attacked, you may have to defend against multiple attackers and to deal with them you will have to kill quickly. At level 7 you always fight at your best when it comes to your charge, from here on you always have advantage on attack rolls on the last creature that hit your charge with an attack or damage from a saving throw, if a new creature should successfully hit them while you are fighting another the new one now has the status.  

Their pain is mine

attacks have failed blocks the blows have snuck through, your charge faces mortal wounds the only thing left is to try and take as much as possible to negate some that is going towards them. At level 10 you are hardy enough to take some damage for your charge and keep fighting, as long as you are within 5f of your charge and nothing obstructs you two fully (say a stone wall) you may choose to take half their damage from a successful attack roll. 

What they care for I do to

You can't expect to just defend one person all your life, your charge will make friends form bonds fall in love and have children, and you will need to put your all into protecting them to. At level 10 the bonds your charge has formed are clear and some new charges need to be added, pick to new characters they now act as charges as well (though resources do not stack) for all ability's bar, Even in death I serve.

They give me strength

You do not just defend these people for money or fame. You believe in them you believe in their cause and seeing them rise and become stronger give you inspiration being around them. At level 15 you are enamored with their progress, as long as you are with 10f of one of your charges you have advantage on saving throws. 

Brutal strike

You've already put your best in to protecting your charge by fighting at your best against all those who attack them, now it's more about hitting that just bit harder to deal with the problem sooner. To this at level 15 gain both ability of brutal critical (though yours is a d8) and you now crit on a 19 as well. 

Even in death I serve

There will be battles where no matter how hard you try it will come down to them or you and it must always be you, do not give in take the blades, survive the fire, fight till you have won and your charge is safe or you have failed and life is not worth it anymore. At level 18 you have fought with your charge to long to let them die, and trained to hard to just keel over and die when the icy grip takes you. Now when you hit 0 hit points you may instead remain up and fighting as long as you stay with 30f of your first charge, while in this state you take damage as normal and would fail death saves from blows as normal, besides moving away from your charge passed 30f three other ways you may be taken out of this state is either. 1 the battle is won and initiative ends, 2 your charge is brought to 0 hit points or 3 your body is reduced to nothing, either way when the state is over you fall to normal d&d death rules including being dead if you took enough blows to auto fail all three death saves.