As the medic, your primary objective is to stay alive. If your ally is running somewhere stupid, don't follow him. Don't latch on to a single teammate and just keep him alive; keep everyone around you overhealed all the time.
If you are a good medic, your allies will protect you. If an enemy is coming straight for you, run towards an ally who can take him. Generally, as a medic, you should not be engaging in combat unless it is your last option.
If you keep your team healthy, they will have no problem keeping you alive too. Just stay out of the way.
I'm going to restate this point because it's extremely important: do not follow your teammates into certain death.
Medic can be a frustrating role because they can't do anything without competent teammates, but every team needs one.
As a Medic, you don't have too much of a defense against any class, much less a Scout, by yourself. If confronted by yourself, you have maybe three options:
- Try and hit the Scout with your Syringe Gun - if you can track them quickly enough. Don't have a Syringe Gun equipped? You're most likely out of luck, I believe one would encounter difficulty trying to hit a Scout with a Crusader's Crossbow.
- Pop your Übercharge and run - if you have an Über.
- Try and hit the Scout with whatever melee weapon you have - if they don't run out of your weapon's range before you hit them.
By yourself, you have no real viable options, especially when a Scout with proficient aim can two-shot you with a Scattergun faster than you can track and pin them down with a Syringe Gun.
The only real weapon you have is your teammates: therefore, you should never fight an enemy by yourself unless you have no other option - instead, help your teammates fight the enemy by healing them.
If you ever find yourself alone and confronted by a Scout, only two of the above options are viable:
Whichever option you choose, as @badp mentions in this question's comments: it would be wise to also call for help (the default keybind is C+1).
This related Arqade question comes to mind: the top answer of that question covers this question well (and probably better than I can), so I'll copy and paste it (with some added emphasis):
As the medic, your primary objective is to stay alive. If your ally is
running somewhere stupid, don't follow him. Don't latch on to a single
teammate and just keep him alive; keep everyone around you overhealed
all the time.
If you are a good medic, your allies will protect you. If an enemy is
coming straight for you, run towards an ally who can take him.
Generally, as a medic, you should not be engaging in combat unless it
is your last option.
If you keep your team healthy, they will have no problem keeping you
alive too. Just stay out of the way.
I'm going to restate this point because it's extremely important: do
not follow your teammates into certain death.
Medic can be a frustrating role because they can't do anything without
competent teammates, but every team needs one.
The second answer to the question is also very informative. I won't copy and paste all of it here, just this one excerpt that is worth mentioning:
If you are with a large group, you don't need to be up at the front line.
In summary: the only real weapon you have against Scouts (and the majority of the other classes) are your teammates. Don't venture too far from your teammates, because if they're any good, they will protect you (and you, as a good Medic, will protect them by healing them).
Best Answer
Turn to look at your Medic and pay attention to the healing beam. If you see yellow streaks on the beam, and you see glowing yellow lights on the gun itself (without custom skins), it's a Kritzkrieg. If the Medic's backpack appears different than usual, and you see yellow and blue/green streaks on the beam, it's a Quick-Fix.
You can also watch the Medic's charge rate. If it's going up pretty quickly, chances are it's a Kritzkrieg or Quick-Fix. After a while of observing and comparing charge rates for all the mediguns, you'll be able to tell the difference at a glance.