哪位大神帮忙翻译一句话呗.它们之间的关系常在一瞬间发生变化——化敌为友或势不两立：为敌时绞尽脑汁,互不相让；为友时,亲如

their relationship changed immediately——they turned from friends to enimies.
They were as close as brothers when they were friends; they are fighting against each other when they become enimies.

The relationship between them often shifts instantaneously-from implacable foes to friends or vice versa. They fight against each other by all means when they are antagonistic or otherwise be intimat to each other like brothers when they are friends, bearing no grudge at all.