The Sentinel
Sanarir pushed away her game console and glanced at the screen displaying the edge of the Milky Way Galaxy. All was calm as usual, nothing alive drifting in space. She sighed and stared at the swirling black portal in front of her.
It was a portal to the Milky Way, the most desolate galaxy in the universe. All of the other portals she had watched over presented an occasional disturbance but not this one. She had felt so disappointed when she was assigned to it for the next three lunar months. But as a proud Sentinel, she had no choice but to take her duty seriously and make sure nothing passes through the portal.
She began to play again when the lights dimmed. Surprised, she looked up and saw the portal had grown so large that it nearly covered the light source. The portal is opening! Someone is coming. Or something. 
Sanarir raised her laser gun. The portal grew ten feet in diameter. A small white object pushed out of the infinite blackness. It was a human hand covered in strange clothing. It was followed by an arm, then a head in a giant globe. It’s not a human like us, it’s a human from Earth. That white attire, that’s their spacesuit, it’s an astronaut! The astronaut emerged from the portal and reached for the laser gun at its belt. But Sanarir was faster. She shot at the gun and destroyed its trigger. The astronaut cursed.
Still pointing her gun at the astronaut, she switched on the communicator and set it to her own language and the most common language spoken on Earth.
“Who are you?” Sanarir asked. The communicator’s microphone picked up her words, translated them in the Earthling’s language and a robotic voice read out the translation. The astronaut answered.
“I am Will Bennet,” the communicator translated.
“How did you travel so far from your home?” Sanarir said.
“What sort of game is this?”
Sanarir blinked.
“Game? This looks like a game to you?”
“Enough! Just kill me already. I am done being hunted.”
“Who is hunting you?” Will glared. “Answer the question!”
“Your friends.”
Sanarir frowned.
“You are lying.”
“Then who hijacked my rocket? Who killed my partner? Who tortured me?”
A web of metal flashed by Sanarir and covered the astronaut. Blue sparks crackled as the metal net gave Will a mild electrocution, forcing him to his knees. Sanarir turned and saw another sentinel, Mrivolog, his arm outstretched, clutching a shooter.
“I was interrogating him!”
Mrivolog lowered his arm and shrugged.
“He is dangerous.” Mrivolog took off a translucent sphere from his belt. “He invaded a nebula maintenance ship, injured three crew members with a stolen laser gun and escaped through portal R-097.” He pressed a switch on the sphere.
“What are you doing?” Sanarir asked. “No wait, he has to go through trial-”
Mrivolog tossed the sphere at the astronaut. It cracked open in mid-air and a new dark wormhole transpired. Will gasped as the wormhole’s powerful gravity pulled him into its depths.
Sanarir shook her head.
“This is wrong.” She walked towards the wormhole. “I am going to bring him back.”
“No! Let him rot.”
Sanarir ignored him. Suddenly a flash of laser zoomed by, barely missing her. Stunned, she turned to see Mrivolog pointing his gun at her.
“Get back here, Sanarir.”
“What is wrong with you? I have never seen you like this. If I didn’t know any better, I would say you are afraid.”
“Just let it go.”
“Why?”
“Enough! You ask too many questions. You-hey!” White fumes spewed between them, causing Mrivolog to cough and back away. During their conversation, Sanarir had discreetly deployed a smoke screen. By the time the smoke cleared, Sanarir was nowhere in sight. She had slipped through the wormhole.
A river of molten rock flowed just beside her. She was standing at the edge of a volcano in a rocky plain. A star cast its scarlet rays over the barren landscape, with jagged rocks spilling long dark shadows on the ground. The place looked familiar somehow. Sanarir looked up at the stars, searching for a known constellation that would indicate her location. Finally she spotted one. Great, we are on Zlenos, which orbits a dying red supergiant, its core had already begun fusing silicon. We have only minutes, if not hours, to get off this planet before the supernova. She looked around and saw a group of the planet’s inhabitants gathering around a white object. It was Will. He was recoiling from the jaws of alien predators.
Sanarir shot the creatures with her laser gun. Some of them turned to her and snarled, baring enormous fangs. They were human-sized bipeds with backward-bending knees, eight fiery red eyes and horns protruding from their bat-like wings. Cridons. A dozen Cridons flew towards her, claws raised. She fired at them and rushed towards Will. A Cridon swooped down and scratched her arm. She ducked behind a large rock and shot it down. The scratch on her arm hissed. Cridons had holes in their claws for injecting acidic liquids. Luckily the acid did not burn right through her suit, it only weakened the material.
She ran to Will, shooting Cridons along the way. She dropped to her knees beside him and unlocked the metal net that was binding Will’s arms.
“What are you doing?” he said.
Sanarir shot three more Cridons.
“Saving you, what else?” She handed him a spare laser gun. “Aim for the head.”
They shot many Cridons but more and more began to appear. They were being overwhelmed. We are losing ammunition.
Will cried out. Sanarir looked back and saw a Cridon carrying Will away in its clutches. He had lost his gun somehow and was struggling to free himself. She ran after them but was forced to stop when she came to a river of molten rock.
She glanced at the lava flow, the Cridon was hovering above it. She took aim.
“No!” Will shouted. “Don’t shoot! Don’t shoot!”
She shot.
Will screamed as he and the dead Cridon fell. The creature dropped into the glistening lava. Will landed on a large rock beside the sinking carcass, in the center of the lava flow.
By this time the other Cridons had reached Sanarir. She was firing at them when she finally heard Will.
“Don’t ever do that again!” he said.
“You are welcome,” Sanarir said. She ducked out of a Cridon’s way and shot it. “Can you come to this side?”
“Hope so.” She looked back and saw Will jump onto another floating rock. The rock carried him further down the lava flow. Finally he summed up the courage to jump onto land and run to Sanarir, Cridons chasing him.
Suddenly all of the Cridons flew away.
Will stopped beside Sanarir.
“Why are they leaving?” he asked.
Sanarir glanced at the star briefly. It is time.
“We have to go.” This suit will not withstand such intense gamma-rays. She pulled out another sphere. We cannot go back to the station. Mrivolog is waiting for us. We need help. She tossed the sphere. “Now!”
Blinding light flashed everywhere. The supernova had begun. Sanarir pushed Will towards the wormhole. The last thing she heard were the screams of Cridons.
* * * * *
Weeks later, Mrivolog and a group of rogue Sentinels were imprisoned for kidnapping, torturing and murdering weaker life forms (including Earthlings) for recreation. Will was returned to Earth safely on the condition that he would never speak of these events again (he did not mind, since no one would believe him anyway). Sanarir was praised for her bravery and as the years went by her numerous adventures finally made her Guardian of the Nevorius Supercluster.