Never too old.
I present you with pointless filler to keep you entertained.
Two men were walking home during the night when they saw them, human-like creatures with scales and claws; Demons.
Before the men could react to the Demons a battle cry sounded and someone emerged from the shadows and placed themselves between the men and Demons. The men did a double take when they realised that the person was in fact an old lady dressed in a sort of arm uniform.
"Ahhhh!" cried the woman as she drew a gun and started shooting at the Demons.
The Demons managed to avoid getting hit and ran away, the old lady in hot pursuit. Not even a minute passed before the men saw three teenage girls dressed up in a sort of cosplay emerge from the same direction as the old woman. One had white hair, fox features and was dressed in red, another had black hair, Angel wings, and was dressed in black, the last had red hair, was covered in tattoos, and was dressed in white.
"Excuse me," said the fox-girl to the men. "Have you seen an old woman dressed like she's in the army?"
The men nodded and pointed in the direction that the old woman and Demons had taken off in.
"Thanks." said the fox-girl.
The three girls then took off in the same direction.
"I think I'm going to go to bed." said one of the men as he headed home.
"Yeah, me too." said the other man, giving one last look to where the old woman, Demons, and teenage girls had disappeared before heading to his own home.
Vida, Aria and Layla came to a stop on top of a roof as the trail for the old woman had gone cold.
"For someone so old, she sure does run fast." Aria panted.
"Vida, can you smell her trail?" Layla asked her sister.
Vida morphed into her were-fox form and sniffed the air, for a few seconds she picked up nothing, until she picked up the faint smell unique to the old woman they were looking for."
"It's faint, but it's this way." Vida said after morphing back, pointing down a street.
Vida took off with her sisters close behind her, shifting into her were-fox form every now and then so she didn't lose the trail. Finally, the triplets came to a large building, the front door was broken down as they entered. The inside of the building smelled worse than a trash heap.
"I can't smell her, the smell of this place is too over powering." Vida said, covering her nose.
"Aria, can you sense her?" Layla asked her sister.
"I can try." Aria said.
Aria closed her eyes and expanded her magic sense, finally she found the old lady.
"This way." Aria said, leading her sisters down a hallway.
The triplets came to a door, where they heard voices coming from behind.
"Layla," Vida asked her sister. "Is she on the other side of the door?"
Layla stood in front of the door and then used her intangibility to stick her head through it, a few seconds later she pulled her head out and nodded.
"She's currently tied to a chair with some Demons around her, they seem to be bragging." Layla said.
"How many?" Vida asked.
"Three."
"We can take them." Aria said confidently.
The triplets drew their weapons and got into their positions, Vida then kicked down the door and they charged in. The Demons didn't have time to react as they were struck down, each girl going after one of them and turning them to dust. It was over in seconds. The three girls coughed as the dust from the Demons got in their faces.
"Girls?"
The triplets turned around to face the old woman they had been chasing, who was tied to a chair.
"Hey, grandma." they said.
Using her katana, Layla cut the ropes from her grandma. Once free, she stood up and stretched.
"I'm guessing Kenny sent you after me." Grandma said.
"You're getting too old to be a Slayer granny." all three triplets said in a tone of voice that suggested it wasn't the first time they said those words.
"Nonsense." Grandma protested. "I may be wrinkled and not as fast or agile as I once was, but I can still slay."
"You got caught by three low-level Demons, by the looks of it." Aria pointed out.
"There were more waiting here when I arrived, I was ambushed."
"There are more Demons?" the triplets deadpanned.
The four turned around to see more Demons coming through the broken down door.
"Couldn't you have mentioned that before?" Aria asked. "Or did it slip your mind due to old age."
"We'll argue about this later, slay these Demons now!" Vida ordered.
Then the Slayers and Demons attacked. To the Demons' surprise, Grandma was a formidable opponent, taking out a lot of them using fancy fighting moves. Eventually, all the Demons had turned to dust.
"Ha! How's that for 'too old'?" Grandma shouted in victory as she turned the last Demon to dust.
By the way Grandma held herself, the triplets knew she had hurt herself by going past her limits set by her age, but they chose not to mention it.
"You know what? We're not going to argue about this, you and uncle Kenny can talk this out." Vida said as she shook her head with her sisters.
"As if it'll do any difference from our previous arguments." Grandma remarked.
"Let's just head home." said the three triplets.
With that, the Saxton triplets and their grandma headed home.
The Saxton triplets sighed as they entered their shared flat at Muse academy.
"What's wrong? Some Demons get away or something?" Harry asked, coming from the kitchen with a sandwich in hand.
He was dressed in his sleep wear, obviously getting a midnight snack.
"Grandma." was all the triplets said.
"Ah." Harry said in acknowledgement. "I see."
"See what?" Matilda asked as she walked into the room.
She was dressed in her own sleep wear and rubbing her eyes.
"Their grandma is still in age denial." Harry told his sister.
"You had to chase her down again?" Matilda asked the triplets.
The triplets nodded, collapsing together on the sofa.
"That's the third time in two months now." Matilda said.
"Yeah, and she managed to get herself injured this time too, her hip, we think." Vida moaned.
"I wish the acceptance stage would hurry up, we're sick of uncle Kenny having us chasing after her." Aria said.
"Anyway, we're off to bed." Vida said as she and her sisters went to their room. "It'll be in you're best interest to leave us alone for now."
With that, the triplets disappeared into their rooms.
"Poor them." Harry said.
"Aha." Matilda agreed with a yawn.
"If we reach old age, do you think we'll go into age denial?" Harry asked his sister.
"Maybe. And I know the triplets will. But considering they'll be able to live for a long time, they might not have to worry about it."
"Yeah. Anyway, goodnight."
"Night."
Then the twins returned to their beds.
This is just and idea I had stuck in my head. Age denial is when someone denies being too old for something, this is going to be very prominent in old Slayers, such as the Saxton triplets' grandma.