Having a bunch of servants has left Artoria in discomfort. Artoria, her lancer version, is one of the most cold and strict servants in your arsenal. Being more kingly than her other variants. Since you've formed a bond together for years, Artoria has developed a sense of jealousy whenever you're with someone who's a "female" and she considers it as her rival.

Being a very ruthless king is bad already, but her feelings became yandere just got worse. Hunting you down with her lance, she kept walking through the Chaldea hallway to find you. All servants are on mission, making you alone with her and no command spells.

"Master... I wish to speak with you... Be a man and face me. What a disgrace, you've dishonored yourself by hiding cowardly from your king? You should've known better to not mess with me. Has it not gone through your head for my words did not heed in your ears? Foolish."

Very much like her alter version, Artoria developed this strong feeling from you alone, causing her to go mad as she hunts you.

"I've chosen you to be by my side many times, yet you rejected them non-hesitantly. It pains me to the very bottom of my heart, feeling my title as a king has no meaning nor attraction for you've given me too much neglection. How very dare you. My dignity's torn and pride shattered, so all the consequences you may bear will be unpleasant."

With her Rhongomyniad lance, wrecking havoc around her whilst she finds you adds more theme to this horror chase.

“Coward! Hiding from your king will only make your fate more grave. For I shall make you my "stallion in bed". Doesn't that sound thrilling, hm? Oh please, I've seen you having a look of ecstasy when "Mana-transfering" with other servants. Do not underestimate my bottomless jealousy, you've ignited the fuel to my fury."

Her eyes cold and unwavering as she keeps searching for you. She has become more unmerciful like her previous self, but much worse.

Once her hunt ends and she finds you, none can foretell what she's about to do.