make peace 和解
hold a grudge 怀恨在心
settle a dispute 解决争端
repair relations 修复关系
old grievances 旧怨
1. There is bad blood between the two companies.
两家公司之间存在深深的积怨。
2. The brothers had bad blood after the inheritance fight.
在继承权之争后，兄弟俩之间产生了仇恨。
3. Despite the bad blood, they decided to work together for the sake of the project.
尽管有旧怨，他们还是为了项目决定合作。
A: Why did they refuse to collaborate on the new product?
A：他们为什么拒绝在新产品上合作？
B: It's because of the bad blood from the previous contract dispute.
B：那是因为之前合同纠纷留下的积怨。
1) 深仇大恨
2) 不和与敌意
3) 历史遗留的矛盾
1. 怨恨；仇恨；不和（通常指因过去事件而产生的长期敌意）
e.g.
There was bad blood between the two political parties.
这两个政党之间存在深刻的敌意。
noun
1. Deep-seated ill-feeling or hostility, often resulting from a past conflict or grievance.
Synonym: hostility, enmity, grudge