So you want to be buddies with Papyrus? He desperately needs one, so this is good news. Also, killing him is probably one of the darkest things you could do in any game. So, y’know, it’s best not to be a complete monster.

This guide will outline how to win the boss fight with Papyrus whilst doing the Pacifist run of Undertale. I’ll walk you through dodging his attacks so that you can eventually trigger his mercy phase. This will convince him to go out with you, allowing you not to kill him.

The Battle:

After leaving Snowdin to progress in the game, you will move into a gradually more dense snowy screen and in this you will encounter Papyrus alone, struggling with his desire to befriend you. If you have successfully not killed on purpose up to this point you will receive this correct dialogue about his mixed feelings as opposed to how in the Genocide run, he believes you are going down a dangerous path.

In the first battle choice want to choose “act” and then “flirt.” This will have you successfully flirt with Papyrus, triggering him to explain that he is a skeleton of high standards. This is when you will choose the “I can make spaghetti” option, defeating his attempt to defend his heart from your charms.

After meeting all of his one spaghetti standards, he will agree, initially, to go on a date with you. Though he plans to date you, he wont give it up easy and will still attack you (having to dodge this attack is unavoidable.) This one isn’t difficult to dodge as all you have to do to is not move down into the small bones moving below you.

You can choose to “insult” or “flirt” and both will progress you into another attack where you won’t need to move. However, after that second attack will come his special “blue attack.” If you don’t move, you won’t get hit but you will become blue at the end of the attack regardless. You will immediately want to press “z” to jump over a small bone.

Now, this could easily be the final straw in ending someone’s pacifist playthrough; he makes you BLUE. Keep in mind that you want to get to that date though. Focus on your goal of mercy.

At this point, the music will have switched into a more exciting remix of Papyrus’ theme and the way you control your heart will change. You now will be affected by a gravity that will pull you do the bottom to the battling frame, requiring you to jump to avoid obstacles.

It’s easiest to choose “spare” in the “mercy” option from here to progress. Be prepared for a series of dodging frames. The first frame will be two small bones and a medium sized bone coming from the left to get you used to the jumping mechanic. This is pretty self-explanatory — for small bones, do a short jump and for medium bones do a slightly longer jump.

For the next window there will be one small bone, several medium bones, and your first large bones. For large bones, you will need to reach the apex of your jump height or reach the apex of your jump height and actually move your heart to the side, to clear them.

The next frame will have bones coming from the opposite direction, now. This will be the first major “mix-up” frame. You will need to clear a large bone and reach the “ground” quickly enough to clear the next upside down bone immediately following it. There will then be some quick, normal jumps and another hanging bone to duck under.
From the same direction, the next frame will have some normal, mostly long jumps and your first serious blue bone to dodge. For this and all blue bones, stay completely still to avoid it. When you successfully dodge it, don’t celebrate for too long as there will be a fast small bone to jump over coming from the opposite direction.

Papyrus will be preparing for your date at this point.

The next frame will introduce two new types of obstacles: the bones with a specific area to pass through and the graduating in size bone line-up that takes the shape of the the full arch of your jump. The bones are coming from both sides now, as well. For the first type, attempt to jump to the correct height and then move through the spaces between the bones to avoid getting hit. For the second type, just make sure to hold down your jump for its full time.

The next frame will have specific hole obstacles (a short jump followed by a longer jump), a blue bone, normal jumps, and two specific hole obstacles coming at you from both sides, short jump and don’t move for that one.

The next frame will be a series of long, full jumps over stacks of bones. It’s simple. The next will be slow-moving bones coming from both sides; this is about timing and not jumping too high. The next will be the same as the last but with even shorter jumps. The next will be a frame full of specific holes to move-jump through.

After this will be more of the same specific jumps, followed by the most difficult obstacle, the moving holes you need to clear. Getting past these is about knowing where they are going to be when you jump into them. After this will be some diagonal angles you will need to clear. Following that will be a frame filled with small jumps and no jumping for the blue bones. The next frame will have two big jumps.

This is when you will start wanting to utilize your ability to move backward from the obstacles to position your jumps. If you can get to this point without taking damage you will be fine up until the point of Papyrus’ special attack—it won’t work out and it will result in a dog munchin’ on a bone. The dog won’t hurt you, go over and pet it. Papyrus will do a normal attack instead.

The normal attack will be a long-form version of the frames you have already been through, mostly non-positioning jumps. You will face the dog from earlier, only this time he will be aggressive and able to lower your HP as he runs toward you, jump over him. You will also have to jump over the word “cool” and the word “dude.” Then there will be small person on a skateboard. Immediately after the skateboarder will be a jump that allows you to extend your jump time to clear a huge bone structure, so hold down your jump button until you fall again.

This is, however, when the most deadly obstacle of all will enter the frame. A very slow-moving small bone will creep toward you. Don’t be tricked by this one. I never let it hit me but I am positive that if you do, it will erase all of the files on your computer. Beware.

With that you will be offered one more chance to “spare” Papyrus. Papyrus will instead spare you. And voila! You will have defeated him and will be able to progress, having let another monster live and going on with not attempting to raise your level. Good job.