When she was three years old, Lin asked her mother to teach her metalbending.

'Oh Lin.' Toph said, 'There's no way you'll be able to metalbend yet. You've only just started teaching yourself earthbending. When you've mastered earth, you can learn metal.'

'And then I'll be as great as you!' Lin giggled excitedly.

'Well.' Toph replied. 'I'm the greatest. But we shall see, if you want to try.'

.-.-.-.-.-.-.-

When Lin was seven she metalbent for the first time, on her own, by copying Toph one morning in the back garden. This earned her a pat on the head from Toph.

'Not bad, kid, not bad.' The greatest earthbender in the world praised her.

'When can I start training, mum?' Lin asked, 'now that I can metalbend, and I've almost mastered earthbending too, I can train with you, right?'

'I'm kind of busy right now, Linny. Lots of stuff with this guy called Yakone, and Suyin and everything. Maybe sometime later, when you're better.'

-.-.-.-.-.-.-

When Lin was ten, she got her first training session.

'Try HARDER!' Yelled Toph. 'For all I can tell, you're a weak rookie in the Academy who hasn't got the greatest earthbender in the world for a mother! You're not getting the hang of it! You're not picking it up like I did. You're not focusing on the particles of earth.'

Tears leaked from Lin's eyes, turning the thick dust and grime on her face into mud. With a yell she ripped apart the sheet of solid steel in front of her.

'Finally.' Toph muttered. 'I taught myself to be a master, you know. When I invented metalbending, it only took me four years to master it.'

Lin stood up from where she had fallen backwards onto the ground from the effort ripping up the sheet had cost her. 'You never mention that I learnt at the age of seven, mum. It's harder to learn when you're younger.'

'Quit your complaining.' Toph growled. 'In the two and a half years that you've had metalbending, you've done nearly nothing. You aren't making progress.'

'Fine.' Lin pointed at Toph. 'You don't teach me. I'll learn metalbending myself, I'll… I'll teach myself, just like you taught yourself! And I'll come back to you when I'm a master and show you that I can be as great as you. That I can metalbend.'

'You can try, Linny.' Toph scoffed. 'Come back when you're fifteen or something and then expect me to pat you on the back and smile. You're not getting the hang of it, and you never quite will, if you ask me.'

Lin walked away, and in her anger managed to tear the metal front door off its hinges as though it were paper.

-.-.-.-.-.-.-.

Lin came back to her mother when she was twelve and Toph was chasing criminals on the beat. Lin used metal cables to swing through the air and stop her mother's seismic sense detecting her, and managed to deftly capture the three Triad members Toph was chasing almost before anyone realised what had happened.

'There.' Lin said triumphantly, panting somewhat. 'I'm a master now.'

'Mm.' Toph was impressed on the inside, really she was. Very, very deep down, she was proud, but that pride was extinguished by a sea of fear that Lin might after all be as great as her. 'You picked it up better than I thought you would. But you still can't get the hang of it properly; you're not picking it up in the way I picked it up. You don't own the metal, you just utilise it. That's the coward's way of metalbending, Lin. Maybe I should have trained you after all.'

'I do not need you to train me.' There was cold fury in Lin's voice. Every officer watched the two, and Lin turned to them. 'One day, I'll be Chief like you, mum. And I don't care if you think I'm useless, I'll prove myself to be a better Chief of Police than you ever were! And I'll become Chief to prove to these people that I've got your bending skills.'

This was a lie. The only reason why Lin wanted to become Chief was because she desperately needed to have her mother's praise, and now she was angry enough to want it even more.

-.-.-.-.-.-.-.-.-.-.-.-

Near the end of Toph's career, crime rates soared more than they had ever done before in the City. Whispers went round that the Chief of Police was no longer what she once was. Some predicted an early retirement, and sure enough, within a year the legendary Toph Beifong left the Police Force for good. She appointed her second-in-command as her successor, but by popular demand after a very short time the position switched to her eldest daughter, Lin Beifong. Some said that Lin ruled with an iron fist, some said that she was only there because of legacy and some said that she must simply be better than her mother. Whatever it was about Lin, though, the crime rate dropped again under the young Chief, leaving the city in a state of peace it had not seen for a fair few decades and every police officer swore loyalty to Lin with an unrivalled pride.

'I'm so proud of you.' Tenzin whispered to her as she came to Air Temple Island after work one day. Lin smiled, and though it wasn't forced, her mind was somewhere else. She loved Tenzin, but there was one person whose praise would mean even more to her. It was funny that it turned out that way, Lin thought. The thing you wanted most was always something that you would never get.

-.-.-.-.-.-.-.-.-.-.-.-

The last time that Lin saw Toph was five years after Lin became Chief. Toph seemed to be avoiding Lin by frequently staying at the Beifong mansion in Gaoling and presumably visiting Su. Lin had not been brave enough to see her mother before because there was an ominous feel to the whole idea, but Tenzin had just asked to marry her and she felt as though she could handle anything. So she tracked down her mother in a seedy bar in Republic City.

'Hey, Chief.' Toph said. 'Come to arrest me?'

Lin looked carefully at her mother. The woman wasn't drunk. Good.

'I need to ask you something.' She said, sitting down on a rickety chair.

'Ask away.'

'Did I finally pick up metalbending?' Lin asked, a dangerous razor sharp edge to her voice. 'Did I please you, the best in the world? Did I make you proud, Sifu?'

Toph considered. She had never wanted Lin to become Chief of Police. 'You want the honest truth?'

Lin nodded.

'Neither you or Su ever really picked up metalbending, in my opinion. Not in the way you should have.'

The chair clattered to the floor and Lin kicked it to one side. Strangely, Lin didn't look angry, just final, and her sigh was one of resigned devastation.

'So I guess that's it then.' She said at last, after a long pause. 'I'm sorry I'm not good enough, Toph. But then again, I hear from people – officers who know you well - that it's impossible to please you.'

She felt like swearing, or screaming, or bursting into tears, but her anger was too strong, her hurt went too deep.

So she walked out of the bar, and returned to the Police station with an iron mask for a face.

-.-.-.-.-.-.-.-.-.-.