Summary: I knowingly trained my replacement at work, as I had a higher-level role but was expecting to leave due to other commitments (i.e. it wasn't a "ruse" by management, for example). I would like to know how, or if, I should represent this on a resume.
A couple of years ago, I was hired as a "summer student" in an Application Support (2nd tier support) role.
In due course I became very competent with my work and developed a strong relationship with my coworkers.
I then found out that one of the people 'John' who worked in first-tier support was out on long term disability, and also that the first-tier team were to be contracted out (outsourced). The company intended to move John into my role once he was able to return in a couple of years, since I was not expected to stay.
Close to the end of my term, I requested they extend me while John was still on leave, and they obliged. I ended up staying there until he returned, and spent the next two months training him until he could fulfil the role, after which my contract ended.
How would you describe this situation on a resume as a bullet under my previous job? I feel like the phrase "Trained employee responsible for taking these positions responsibilities" might bring into question why I'm no longer there, but there is no bad blood between my previous employer and I.
Clarifications: HelpDesk is considered first tier support, where our tickets come in and more trivial tasks can be completed. If they require higher privileges or helpdesk can not solve the issue they triage it to second tier. Application support is second tier support for all software based issues.